Monday, June 29, 2009
We have official even-strength performances available from NHL.com since 1998-99, and one of the things I have been tinkering with is estimating even-strength save percentages for prior years based on goalie overall save percentages and special team statistics like power plays against and power play goals against.
I compiled the even-strength numbers for the consensus top 5 goalies of the official save percentage era (Roy, Hasek, Brodeur, Belfour, Joseph), and filled them out by estimating their even-strength records for the remaining years of their careers. I'm still working on getting the best fit, so these numbers will be further refined, but I believe they give a good approximation. Once again, what many people see as a "Top 3 and Lesser 2" is more probably a "Top 2 and Lesser 3", perhaps even a "1-1-3" ranking:
Dominik Hasek: .935 even-strength sv%, .914 league average, +.021
Patrick Roy: .921 even-strength sv%, .906 league average, +.015
Martin Brodeur: .922 even-strength sv%, .916 league average, +.006
Curtis Joseph: .917 even-strength sv%, .911 league average, +.006
Ed Belfour: .916 even-strength sv%, .911 league average, +.005
I also thought it would be interesting to post a breakdown of seasons by "poor", "average", "good", and "great". I defined poor as a save percentage of below 99.5% of league average, an average season as from 99.5% - 100.5% of league average, good as 100.5% - 101.5% of league average, and great above 101.5% of league average. Here is how each goalie ended up doing in each season they faced at least 500 shots against:
Hasek: 0 bad, 0 average, 5 good, 8 great
Roy: 1 bad, 1 average, 6 good, 10 great
Brodeur: 0 bad, 7 average, 6 good, 2 great
Joseph: 3 bad, 7 average, 3 good, 3 great
Belfour: 3 bad, 6 average, 6 good, 2 great
There is a consistency argument that can be made for Brodeur over Belfour and Joseph, although some of the bad seasons for the latter two guys were late-career seasons when they were clearly on the decline. Belfour also had one average season effectively spiked by getting traded to the expansion-era San Jose Sharks, who were a legitimate shot quality outlier. In addition, Brodeur almost always tended to play more minutes than the other guys did, so as such we would expect his numbers to less affected by random variations.
If we further restrict it to seasons where the goalies faced at least 1000 shots against, and were between the ages of 21 and 36 (to match Brodeur's career so far), we get the following:
That shows much less of a difference between the bottom three guys, particularly for Joseph who really had his game desert him in his later years.
I still find it hard to see a significant difference between Brodeur and Belfour. There's not much between them other than in the games played column, and one could argue that Belfour closes some of that gap with superior playoff results. Over a 20 year career Brodeur likely gives a team more total value, but if you had to choose one of them to play a key game for you it's pretty much a tossup.
There was also probably little to no difference between Brodeur and Joseph in terms of stopping the puck, once you put the two of them on a level playing field. Joseph didn't age gracefully, but at his peak he was probably better than Brodeur at making the first save. When taking everything into consideration, however, Brodeur has much better non-save skills and that breaks the tie.
In an all-time perspective, if one was to rate goalies based on how they actually played, not based on how well their teams did or how good sportswriters thought they were, then Brodeur should be ranked much closer to Belfour and Joseph than to Hasek or Roy. As I've said many times before, I believe it's a mistake to rank Brodeur up with the latter two, as both of them had 6-7 years of prime seasons at a level well above anything Brodeur ever reached.
I hope to post some more numbers for other goalies when I get a chance. I did manage to run the numbers for Roberto Luongo, since he has done well in similar performance measures. I know it doesn't matter anymore now that he let in 7 goals in one playoff game, thereby rendering all previous results obsolete, but Luongo has a career .929 even-strength save percentage, compared to a league average of .918, for a +.011 difference, with 5 good seasons and 3 great seasons. That puts him on a trajectory to end up somewhere around the Belfour/Brodeur/Joseph range or even a bit above, keeping in mind that Belfour and Brodeur close the gap some when you factor in their apparent shot prevention effects.
Tuesday, June 23, 2009
Chris Osgood had a horrific regular season, and then followed it somewhat surprisingly with two excellent months in the playoffs. This disparity has led to many journalistic screeds about Osgood's clutch ability and his ability to "focus when the playoffs come around" and all kinds of similar thoughts, but having a terrific stretch in the middle of average or below average play is not nearly as unusual as people apparently think.
There is a long list of goalies who have played at Osgood's current level for two consecutive months at some point this season. Unfortunately for those guys, they weren't lucky enough to either make the playoffs, or, if they did play in the postseason, to time their hot streak to coincide with their playoff play (with a couple of exceptions, most notably Jonas Hiller).
Osgood finished the playoffs at .926. Given that the average save percentage usually rises in the playoffs, we can get an equivalent regular season amount by adjusting for the difference between a .915 postseason average and a .907 regular season average. Part of the first figure might be that playoff teams have better goalies on average, but I'm not really convinced of that this year.
Let's say .920 is an equivalent regular season rate. I also set 6 games played in each month as a minimum cutoff. This season there were 22 goalies that played 2 straight months at .920 or better. Fourteen of them had a better save rate over their best 2 months than Osgood has in the last 8 weeks.
The complete list is as follows, with the goalie's best 2 month save percentage in parentheses:
Yann Danis (.945)
Tomas Vokoun (.941)
Tim Thomas (.940)
Chris Mason (.940)
Craig Anderson (.938)
Steve Mason (.938)
Jonas Hiller (.936)
Pekka Rinne (.934)
Mike Smith (.932)
Martin Biron (.931)
Ryan Miller (.929)
Cristobal Huet (.929)
Niklas Backstrom (.928)
Roberto Luongo (.928)
Henrik Lundqvist (.925)
Nikolai Khabibulin (.923)
Scott Clemmensen (.923)
Carey Price (.923)
Evgeni Nabokov (.921)
Cam Ward (.920)
Ty Conklin (.920)
Miikka Kiprusoff (.920)
There were a number of others who were much worse in the rest of the season than they were in their two best months, a la Osgood. The best example is the leader of the pack here, the Islanders' Yann Danis.
Danis is a great example of the variance of goaltending. In 14 games over 2 straight months, he stopped 481 of 509 shots for a .945 save percentage. The rest of the season, he was at just .868. I suppose according to the cliches he must have been more mentally tough or he just really bore down or something in January and February than during the rest of the season. I think he probably just wasn't all that good and got hot and lucky for a bunch of games in a row. Fourteen games is two playoff rounds, so Danis could have become a legend if he happened to time that streak to begin with the start of the playoffs on a playoff team. Unfortunately for him he's probably a career minor-leaguer, but he'll always be able to look back fondly on that brief glorious stretch where nearly everything sent his way just seemed to hit him.
The hot streaks were all spread out, some had them right at the start of the season, some had them at the end of the season. I find it hard to believe that any of them were voluntary, or why wouldn't the goalie simply do the same thing the entire way?
All athletic performance is variable to some degree. Goaltending is based on angles and percentages, which makes it even more variable than other athletic endeavours. Hot and cold streaks happen to everybody and they can be quite extreme over short periods of time. Most of the starting goalies in the league had a 2 month stretch like Osgood has had in the playoffs. Osgood was the only one fortunate enough to have his hot streak come when the games started becoming meaningful and with the Detroit Red Wings playing in front of him.
In my view, if Osgood was unusually clutch we'd see more evidence of it in his past playoff career, but his results are decent but pretty close to average. If he is able to turn the switch off and on at will, then he must have curiously left it off for quite a few playoff seasons, which doesn't make a whole lot of sense. That leaves us to conclude that he either learned how to be "clutch" at some point in 2008, or he perhaps more likely just got hot at the right time.
Having said all that, Osgood has been unusually hot over the last two playoff seasons, especially at even-strength. Here are his even-strength save percentages compared to league average for the last two seasons, as well as during the preceding decade. Which one does not belong with the others?
Season: Osgood .913, League .916
Playoffs: Osgood .920, League .927
Season: Osgood .910, League .919
Playoffs: Osgood .948, League .927
If we assume that Osgood's actual skill level in the playoffs is .920, the probably that he plays at .948 over 853 shots, assuming an equal team context, is about 0.1%. In other words, extremely unlikely. Part of that is likely the team, though. I think everyone who watched the games would concede that Osgood got a lot of help from his team last season, but this year he has had to do more on his own.
If Osgood has somehow learned how to be a terrific even-strength goalie in his mid-thirties and only decides to play at that level in the playoffs, then he would certainly be a most unique case. To me that explanation seems both illogical and unlikely.
People seem to get all hot and bothered for some reason when they hear the word "lucky" used to describe the result of a game or an athlete's success, so I'll be charitable and won't go there, but let's just say that Osgood's run of strong play in 2009 was certainly well-timed. Streaks happen, most of the time they defy explanation, all you can do is hope they come at the right time and ride them as long as you can. Good for Ozzy, he was a big contributor to his team in the 2009 postseason, but that still doesn't mean the smart money is on him repeating the feat the next time around.
Monday, June 22, 2009
In the over-simplified world of sports journalism or Internet hockey message board-fandom, Marc-Andre Fleury is now an elite goalie. If Chris Osgood had stopped both of Maxime Talbot's shots in game 7, however, then Fleury would not be elite (and by similar logic, Osgood would then be deserving of being immortalized as one of the 30 or so best goalies in the history of hockey). Such is the narrow margin of what constitutes "eliteness".
Is Marc-Andre Fleury actually one of the very few best goalies in the NHL today? I don't think so. He played very well in games 6 and 7 of the Stanley Cup Finals, but I don't think he was that terrific in the postseason as a whole. In fact, Fleury quite likely had the worst overall playoff season of any Stanley Cup winning goalie in the last decade (.908 save percentage), so it seems a bit curious to me to suddenly claim him to be one of the league's best, no matter how spectacular he was stoning Lidstrom with seconds left to play in game 7.
Since the lockout, Fleury's save percentage has been .908 overall and .921 at even-strength. League average has been about .906 and .918 respectively. I don't think the Penguins are or have been a shot quality outlier (except maybe 2005-06), so those numbers probably give a fairly good indication of what Fleury is: An above-average goalie. On a good day, Fleury's athleticism gives him a higher peak than other goalies of his performance range, but he doesn't appear to be a Lundqvist or a Luongo, despite his more impressive jewellery collection.
Fleury is 24 years old, so it is probably reasonable to still expect some improvement. But goalies generally peak earlier than conventional wisdom suggests, and Fleury is likely either just beginning or already in his prime years. He's good enough that most teams would lock him up long-term if they had him, and he will likely give Pittsburgh good goaltending for the next decade or so, but I'm not expecting any Vezina calibre performances (although with Crosby and Malkin up front, the possibility is there for a 45-50 win season that might end up being recognized with some not-necessarily-deserved hardware).
Thursday, June 18, 2009
Both Mason and Backstrom played on strong defensive teams and had high save percentages on the penalty kill. Backstrom led the league at .918, which is just an off-the-charts figure, and Mason was in the top 10 among starting goalies at .885. The evidence seems to suggest that penalty kill results are more team-dependent than even-strength results, and the smaller sample size means that those results are more variable, so it is tough to tell whether they were playing great on special teams or benefitting from some lucky bounces and/or excellent defenders in front of them.
Backstrom's save percentage at 4 on 5 was almost identical to league average at 5 on 5, which either suggests that Backstrom was absolutely phenomenal when the Wild were down a man or that Minnesota is doing something special on the PK. I haven't seen much of the Wild this season, so I'm not really sure how the credit should be split up. Hockey Numbers has the Wild ranked 3rd in the league in shot quality against at even strength and 6th in the league in shot quality against on the penalty kill, so I'm pretty sure Backstrom is getting some quality help.
Mason, as I've observed before, only really had one spectacular month, and has been pretty ordinary in the 2009 calendar year.
Even-Strength Save Percentage Leaders (min. 500 SA at ES):
1. Tim Thomas: 1320 SA, .940
2. Roberto Luongo: 1156 SA, .936
3. Tomas Vokoun: 1514 SA, .935
4. Jonas Hiller: 899 SA, .934
5. Nik Khabibulin: 912 SA, .933
6. Martin Brodeur: 667 SA, .933
7. Mike Smith: 961 SA, .931
8. Scott Clemmensen: 913 SA, .929
9. Craig Anderson: 753 SA, .928
10. Manny Fernandez: 636 SA, .928
18. Steve Mason: 1266 SA, .925
19. Niklas Backstrom: 1633 SA, .923
(League Average: .919)
What is interesting is that there are 2 Bruins, 2 Devils, and 2 Panthers in the top 10 in even-strength save percentage. That seems to me to be pretty unlikely to happen in a 30 team league if there is little to no variation in terms of shot quality against across teams at even-strength. That might raise a few question marks about the results for Thomas and Vokoun, but I think both Fernandez and Anderson are above-average backups. Thomas probably had an easier job than average in Boston, but his performance is still likely far enough ahead of everyone else's that he remains in front, all things considered. It is possible to put up a great goaltending performance on a good team, and that's what Thomas did this season.
Who should have finished 2nd and 3rd in the voting? I don't think it really matters all that much, because there is a clear separation between the winner and the runners-up, but I think I would have picked Vokoun and Luongo as the #2 and #3 guys this year. Hockey Numbers has Vokoun ranked 5th and Luongo ranked 7th in shot-quality neutral save percentage, ahead of Mason (8th) and Backstrom (14th), and both faced several hundred more shots against than anyone else ahead of them other than leader Thomas. Behind the Net also has shot quality ratings for 5 on 5 play, and Thomas is ranked 1st, Luongo 3rd, and Vokoun 5th. In 2nd is Khabibulin, and in 4th in Lundqvist, who likely benefits from MSG's biased scorers. I think Khabibulin is another guy who should get consideration as one of the year's top goalies, as he quite possibly outperformed Backstrom and Mason.
Mason vs. Luongo is a pretty close call, since they had pretty similar seasons. Both of them had a terrific first half, with one month each where they were almost unbeatable, then had some health issues and weren't able to play up to the same level late in the season. They also both significantly outperformed their backups, and their teams did much better with them in net than in their absence. Their overall numbers are pretty similar as well. There's not much between them, and I don't think it is necessarily wrong to put Mason first, but given their track records it's a lot more likely than Mason got lucky than that Luongo did, and that Luongo was better 5 on 5 is enough of a tiebreaker for me.
I think the top 5 were probably Thomas, Vokoun, Luongo, Khabibulin and Mason, with the latter 4 close enough together that it really doesn't make a huge difference how you rank them.
I think 2008-09 will mostly be remembered for goalie injuries. Over 75 starts, which is what he was pretty much assured of hitting without getting injured, Luongo's numbers project to 45 wins and 12 shutouts. That probably would have taken the Vezina over Thomas, especially since one of these years Luongo is going to benefit from the "I can't believe he's never won a Vezina yet!" narrative (see Brodeur in '02-03). I think Martin Brodeur would have put up some gaudy team stats as well, considering his numbers and how well Scott Clemmensen managed in his absence, so it likely would have been similar to 2007 with Brodeur and Luongo facing off for the hardware if fate didn't intervene. Oh well, luck's a part of hockey, as we all know, and this time the guy who benefits the most is Tim Thomas.
Wednesday, June 17, 2009
Is there a big difference between a goalie who plays 50 games and a goalie who plays 65? Most people probably would say yes, and I know that most award voters would agree with that statement. The problem is that I doubt any of them ever tried to quantify the difference. What if the 50 game guy has a .935 save percentage, and the 65 game guy has a .905 save percentage? What about .925/.915?
I haven't seen any evidence that there is a statistical difference between playing 65 and playing 50 in terms of fatigue affecting your play. Fifty also represents the bulk of the season, which means that the additional games played do not have a major effect on the average.
To demonstrate this, let's take a goalie who has played 50 games at a pretty average level on an average team (say, .908 save percentage), and consider two scenarios, Scenario A: He plays the last 15 games like the best goalie in the league (.940), and Scenario B: He plays the last 15 games like the worst goalie in the league (.880). What is the effect on his seasonal numbers?
Scenario A: .915
Scenario B: .901
In both cases, his seasonal save percentage moves just .007, even though the extra 15 games played were either fantastic or horrific. It is pretty unlikely that NHL goalies will put together results more extreme than either of those two over a 15 game stretch.
Do the same thing comparing 50 games to 75 games (adjusting the save percentage assumptions a little closer to say, .930 for A and .890 for B since the games played sample is larger and extreme results are less likely to occur), and we get a split of about +/- .010 in save percentage.
I think that is a safe general rule of thumb to use, that if one goalie is .010 or better than another in save percentage, after adjusting for the team context they play in, and if both goalies have played the majority of games for their teams and you don't suspect there is any large differential in shot prevention between the two, then you can pretty safely say that the goalie with the higher save percentage is better. Even if one has played 70 games and the other has played 50.
Let's do a similar calculation for Tim Thomas this season to show that he was demonstrably better than the two other nominees, even though they played more minutes. Thomas played 829 fewer minutes than Backstrom, and 405 fewer minutes than Mason. If we assume that Thomas would face the same shot rate against if we has to play those extra minutes, we can figure out what stats he would need in that extra playing time to match Backstrom's and Mason's numbers.
To match Backstrom: 3.26 GAA, .884 save %
To match Mason: 3.85 GAA, .778 save %
Tim Thomas this season: 2.10 GAA, .933 save %
Tim Thomas, career: 2.62 GAA, .918 save %
How's this for a stat: If Tim Thomas played in 11 extra games and faced his usual shot rate, he could have allowed 5 goals against and lost every single one of them, and he still would have a better winning percentage and save percentage than Steve Mason.
Decide for yourself how likely it is that fatigue or any other factor involved would drop Thomas below those other guys.
Those are unadjusted numbers, of course, so take that into account. Shot quality measures suggest that Thomas faced tougher shots than Backstrom, but easier shots than Mason. We can calculate the shot quality factors that would be necessary for Thomas to have equivalent performance:
To match Backstrom: Bruins 13% easier SQA than Wild
To match Mason: Bruins 20% easier SQA than Blue Jackets
The typical spread from best to worst in the entire league is about 20%, so to argue that Mason's team-adjusted performance was better than Thomas' you would have to demonstrate that Boston was the best team in the league at shutting down opposing scoring chances, while Columbus was the worst. Even then the two of them would be virtually tied, so it would be a coinflip as to who wins.
Tim Thomas should win the 2009 Vezina Trophy. He should also be the First Team All-Star. I'm pretty confident Thomas takes the Vezina, as I don't even see the argument for either Backstrom or Mason to finish ahead of him, but I'll be interested to see what the writers do. They tend to put more weighting on things like wins and games played, so they might throw everyone for a loop and go with Mason, or even Evgeni Nabokov again.
Tuesday, June 16, 2009
The consistency debate often arises when one goalie has a lot of shutouts and another has very few. Luongo vs. Brodeur in 2006-07 is one example that comes to mind. If two goalies have similar overall season stats and one has substantially more shutouts, that simply means that he must also have had more bad games.
However, I have noticed that this season there have been a number of goalies who have had absolutely fantastic months. Roberto Luongo was almost unbeatable in November, but wasn't nearly as good since returning from his groin injury. Steve Mason was dominant in December, but was been merely average in 2009. How much should a great month contribute to the overall total?
On the other side of the coin, what about one terrible month? How much should a goalie be penalized for that? Henrik Lundqvist apparently has some issue with performance in the month of December. In his career he has an .891 save percentage in December, compared to .921 in all other months combined. This year Lundqvist remained true to form, stumbling through the Christmas season but otherwise playing pretty well. If we take out his December numbers, Lundqvist ranks up near the league leaders.
I decided to go through and knock out the best and the worst month for some of the goalies who might get talked about in terms of the Vezina, and see what was left. There were a few goalies who were downgraded by this method (e.g. Mason, Roberto Luongo, Cam Ward, Pekka Rinne), and some that got a boost (e.g. Lundqvist, Marty Turco).
These numbers are unadjusted and as such are very team-dependent, so as always take that into account. However, if you think consistency is something that should be rewarded, then you should probably go with Tim Thomas for the 2009 Vezina Trophy.
Wednesday, June 10, 2009
For 15 years, the rainfall has been pretty much as expected. There were a few years that it rained less than usual and you had a lot of sunny weather, 1998 for example, but otherwise it's been pretty typical, and some years were wetter than normal.
Last fall, there was a lot more rain than usual. This mostly continued throughout the winter. You've been a bit concerned about the extra precipitation, hoping that that doesn't mean it will continue throughout the spring and the summer. You have some big parties and events that you are planning to host, and you hope that the weather won't put a damper on their sucess.
Suddenly in April and May, there has been some great weather. There have been twice as many sunny days as usual, and you have lots of opportunities to get out and enjoy the sunshine. Everything you planned went off without a hitch.
You are surprised by this, and wonder if it means anything. You remember that rainy days aren't always evenly spread out - sometimes they come in groups and sometimes they don't appear for quite some time. What is more significant, the extended track record or the last couple of months? Is there any reason to expect things will change in the future?
What do you conclude?
A) This is a temporary weather variance, and the weather will likely return to normal.
B) The weather is really clutch in the playoffs
Monday, June 1, 2009
I haven't seen every game Chris Osgood has played this playoff season, and I probably haven't seen him at his best. I do find it a little strange that a goalie can get essentially beaten on 5 shots and still get roundly praised and named the player of the game. Surely a portion of last night's first star billing should be shared with Zetterberg and the goal posts.
The shot charts are saying that Osgood is making more hay in these playoffs from not letting in the easy long shots than standing on his head against the tough ones, which makes sense to me. That's not a criticism, obviously you want your goalie to be making the easy saves. Still, given how rare it is that Detroit gets hemmed in their own end, you have to think that most of the time Ozzy is picking cherries on those shots while the guy at the other end of the ice is struggling to see through the backsides of Holmstrom and Franzen. My sense from having worked with some shot quality measures in a little more detail over this playoff season is that there is still room for improvement.
It is interesting to me that Osgood has suddenly gained a reputation as a good playoff goalie. There have even been some comparisons to guys like Billy Smith or Grant Fuhr in the media. In the event that Osgood finishes the job and pulls down the Conn Smythe Trophy, which I think is a pretty good bet to follow a Wings victory given the likely vote splitting among the skaters, I still don't really see how he fits that description. Other than the last couple of playoff seasons, there really isn't much that deserves to be called "good" in Osgood's record - it's pretty much a nice collection of averageness.
Osgood won a Cup in 1998, but he did it while getting maligned (and in my opinion justifiably so) by observers after posting only the 6th best save percentage in the playoffs that year, an unusually low mark for a Cup winner. Even leaving aside the ability of the Red Wings to play defence, one of the benefits of playing on a great team in the playoffs is a lower strength of opposition since you get to meet lower seeds in the first couple of rounds. The pre-lockout version of Osgood pretty obviously fattened his playoff stats on the also-rans before getting chewed up by the elites. I figured 95 points seemed to be a good cutoff to separate the contenders from the rest. Note the disparity:
Opponent below 95 pts: 27-11, 2.01, .917
Opponent above 95 pts: 18-26, 2.45, .905
(For reference's sake, league average in this period is about .915).
Over the last 2 playoff seasons, the Wings and Osgood have dominated all comers equally. I wonder if they don't even have a greater relative advantage now than before because of their excellent management combined with the salary cap-induced parity around the league. We have to keep in mind the point inflation from the shootout when comparing with earlier results, but as of late the combination of Detroit and Osgood hasn't had the same problem of keeping good teams from scoring against them:
Above 95 pts: 18-5, 1.74, .930
Below 95 pts: 10-3, 1.83, .927
Two good playoff runs are two good playoff runs, but I don't imagine I would find much agreement in the general population if I went back in time to March 2008 proclaiming to the world that Osgood was a clutch money goalie. I imagine I would instead get more than a few curious, if not downright sympathic, looks.
I figure we're getting close to the point where I can get a sense of somebody's ability to evaluate goalies by just asking them if they'd rather have Osgood or Luongo in net for their team in a key playoff game. If they say Ozzy, then it's time to smile and move along and save yourself the hassle.
Having said all that, I think Osgood has been pretty good in these playoffs, all things considered and my eyes notwithstanding. That doesn't mean I would wager any money on Osgood having the same success next season, though, in either the regular season or the playoffs. I'm not even sure I'd bet a whole lot on him continuing the same success in game 3. I imagine the Penguins are going to start catching some breaks or making some shots pretty soon. But maybe I'm wrong altogether and Osgood is just that good at stopping pucks / rolling the dice / playing behind Henrik Zetterberg and Nicklas Lidstrom. As they say, that's why they play the games.