Monday, July 30, 2007

It's All About the Team

Over the last few weeks, I haven't posted much, as I have been working on a stats project, developing a new metric to evaluate historical NHL goalies. In recent years, there has been a big improvement in our evaluation of goaltenders, first as a result of a movement away from team-dependent stats like wins and GAA and towards save percentage as the key metric, and then further refining that by adjusting for era or workload. This is definitely a step forward, but even that ignores probably the most important single factor in a goaltender's success: The team in front of them.

Perhaps the biggest breakthrough has been shot quality measurement (read up on that at Hockey Analytics), which has allowed us to remove the impact of the defence in front of a goaltender, subject of course to the limitations of the NHL's RTSS data. However, these data are only available for the past 5 years or so. How then can we attempt to correct for team factors for goalies throughout the history of the NHL?

We can't, really, at least not with very great precision. However, there are ways to estimate shot quality. I looked at correlations with various variables and team shot quality, and found that the variables that were most closely correlated were overall goals against, and team save percentage. Therefore, to estimate shot quality, we can use the statistics of a goalie's teammates, and by using that as a benchmark, evaluate whether the goalie's performance is exceptional or team-driven.

There are several issues with this, primarily sample size. The elite starting goalies play 70-75 games a year, meaning sometimes there are only a few games played with someone else in the net. Also, I don't have save percentage information from before 1982, so I used goals against average. GAA is very team dependent, but since we are comparing teammates here I consider it to be reasonable to use. I also am not sure how much I can trust shot totals over the years, and according to some theories certain goaltenders are responsible for reducing the shots against themselves through puckhandling, rebound control, etc., so using GAA removes those potential issues. Backups also tend to be weaker goalies, but they also tend to player weaker opponents as well. To adjust for this, I have a subjective method for adjusting backup performance, based on their ability and career record.

In short, then, if a goalie gives up fewer goals than the other goalies on his team do, he is better than them, and is contributing to the team's defensive success. If a goalie has similar stats to the other goalies on his team, then it is likely the team that can be credited with the defensive success. In general, the greater the gap between the goalie and his teammates, the better the goalie.

My main area of interest is to determine who were the best performing goalies of the 1980s - was it Fuhr, Smith, Roy, or Vernon, i.e. the goalies with the rings, or were there other unsung heroes who never received their due? This project is almost completed, so I will be posting some of my findings, especially the cases of goalies who appear to be substantially under- or overrated, and hopefully expand this blog's dialogue to include many other goalies beyond Martin Brodeur.

Thursday, July 12, 2007

Defend Martin Brodeur Here

Thus far, I've made my case that Brodeur is an overrated goalie with an excellent defence in front of him. This is shown by, among other things, the strong performances of his mediocre backups and what other goalies have done in similar defensive systems. He has faced few shots against, relatively few difficult chances, and few opposing power plays. Despite these advantages, he has put up unimpressive save percentage numbers throughout his career.

Brodeur's record in clutch situations in the playoffs is not outstanding, and his overall playoff performance is weaker than the best of his peers. The Devils have had playoff success at times even when they did not receive strong play from the goaltending position.

More than anything, Brodeur's success appears to stem from his durability and his teammates, neither of which are particularly good reasons to rank him as the best goalie in the league, much less one of the best of all time. I have demonstrated that all three of his Vezina Trophy wins were undeserved, and that even despite being favored by voters ahead of statistically similar peers throughout his career, he does not have the award recognition to match the all-time greats.

However, judging by reader feedback, not everyone is convinced by the evidence presented. Here's your chance to defend Brodeur by pointing out errors in my position, or contributing alternative viewpoints and hopefully evidence, statistical or otherwise, in support of Marty.

What am I missing with Martin Brodeur? Does his puckhandling save so many goals per year to make up for any other deficits? His intangibles ("inspires his teammates", "leadership", consistency") are often cited - can they be quantified? If they are so effective, why haven't they shown up clearly in his goaltending record? What else does Brodeur bring to the table that other star goalies do not? Or is it all about the career wins, Cups, and gold medals, and who cares how he got them?

Thanks for the continued feedback, positive and negative, as we continue to search for better ways to evaluate the position of hockey goaltender.

Monday, July 9, 2007

Grant Fuhr's Big Saves - Fact or Fiction?

Myth: With Grant Fuhr making the big saves in crucial situations, the 1980s Edmonton Oilers won a lot of 5-4 and 6-5 games.

Truth: The Oilers rarely played in 5-4 or 6-5 games, and even when they did they were just as likely to lose as to win.

In the popular memory, Grant Fuhr was a goalie that bore down in the final moments of the game, shutting the door on the opposition to preserve 6-5 shootout wins for the Oilers. Unfortunately, this perception doesn't match the historical record. From 1982 to 1989, the Edmonton Oilers won a playoff game 5-4 a total of only four times, and two times they ended up on the wrong end of the 5-4 score. They won 6-5 just twice while losing three times by the same result.

Edmonton did have a very good playoff record in one goal games (26-9). That was partly because they were very good in overtime, going 9-3. It is easy to attribute a strong overtime record to the goalie, but these are Gretzky's Oilers we are talking about, and they tended to score goals quickly. Five of the 12 overtime games were decided before the teams even played 65 seconds of OT. Only four of them went longer than the 4 minute mark. Despite the impressive record, Edmonton's goalies (mostly Fuhr) had a mediocre 4.00 GAA in overtime, nearly a goal higher than their GAA in the first 60 minutes. Edmonton did well in one-goal games, but only about a quarter of their games were decided by one goal because they so often blew out their opponents. Edmonton also did very well in games decided by two goals or more (58-21).

I looked at Grant Fuhr's regular season results from 1985-86 to 1988-89 on to try to see if they matched the playoff numbers. In games decided by 5-4 scores, the Oilers had 6 wins and 5 losses. In 6-5 games, the Oilers won twice and lost four times. I also checked out the results for 6-4 and 7-5 games just to see if I was missing something, but in those games combined the Oilers had 7 wins and 5 losses. The Oilers again had a good one-goal game record (34-21), but it was actually worse (.618) than their record in games decided by 2 goals or more (.640).

Out of Fuhr's 483 regular season and playoff games in the 1980s with Edmonton, he won only 14 of them by 5-4 or 6-5 scores, and 11 of those wins came in overtime, where Edmonton won a lot of games because their offence was so quick to score. Fuhr also lost 13 games by one of those two scores, mostly in regulation time, meaning that Edmonton wasn't really any more likely to win the close high-scoring shootouts than their opponents were.

There is some evidence that the Oilers won more games than they should have, both in the playoffs and in the regular season. From the Pythagorean expected win formula (based on goals scored and goals allowed), the Oilers would have been expected to have won 68.7% of their playoff games and 63.4% of their regular season games between 1982 and 1989. They actually won 73.7% of their playoff games and 66.6% of their regular season games. However, Edmonton platooned their goaltenders, using both Fuhr and Andy Moog. The two goalies had similar stats: Moog's GAA with Edmonton was 3.61, Fuhr's was 3.76 over the same time period. Moog also had a better winning percentage than Fuhr did with the same teams, in both the regular season and the playoffs.

So even if Fuhr was a clutch goalie, then so was Andy Moog, since Moog had better stats and a better winning percentage. What is more likely, however, that one team had two excellent, clutch goalies that led them to repeated Cups, or that the high-scoring Oilers dynasty made their goalies look like winners? Based on the evidence, the second option looks like a pretty safe bet.

Sunday, July 8, 2007

Jeff Hackett

Jeff Hackett is a great example of an underrated goalie who played well but was never really noticed because he almost always played behind weak teams.

Hackett's first four years in the league were all with very bad teams. He broke in with the New York Islanders, and then moved on to the expansion San Jose Sharks, who took only 39 points in their first season, and followed it up in 1992-93 with just 24 points. That year, Hackett faced over 36 shots per game, and the best goalie on the team, Arturs Irbe, had just an .874 save percentage, showing how difficult it was to play goal on that terrible Sharks team.

In 1994, Hackett was traded to the Chicago Blackhawks, where he was slated to be the backup goalie to established star Eddie Belfour. He didn't have a great first year in Chicago, but from 1994-95 to 1996-97, Hackett outplayed Belfour every season, including an excellent 1996-97 year where he posted a .927 save percentage in 41 games. Chicago traded Belfour to make room for Hackett, who was given the starting job for the rest of the year and the playoffs, where Chicago lost in the first round to the defending Stanley Cup champion Colorado Avalanche. Hackett had another strong year in 1997-98, starting 58 games and posting a 2.20 GAA and a .917 save percentage on a 73 point team that missed the playoffs.

After a rough start to the 1998-99 season, Hackett was involved in a blockbuster trade to Montreal. The Habs were just as bad as the Hawks, finishing short of a postseason berth more often than not. In 1998-99, the Canadiens missed the playoffs, despite Hackett's excellent play (2.27 GAA, .914 save percentage). He kept it up the next season (.914 save percentage again) as the Canadiens finished above .500, but were still not good enough for the playoffs.

However, there was a young goalie in Montreal who was pushing Hackett for playing time - the future star Jose Theodore. In 2000-01, Theodore took over, relegating Hackett to a backup role. By then the 33 year old Hackett was past his prime, and could not keep up with Theodore, who quickly became one of the league's top goaltenders, for a few seasons at least. Hackett provided Montreal with two and a half more seasons of solid backup play, before moving on through Boston and Philadelphia, and finally retiring after the 2004 season.

In his entire career, Hackett made just 10 playoff starts. Every one of them was against a 100 point team with either Patrick Roy or Martin Brodeur in the other net. Needless to say, his record was not very good - just 3-7. The average team Jeff Hackett played on had just 72 points. This was despite him delivering above average goaltending most years, and being excellent in several years in the prime of his career.

Hackett's career save percentage was .902, which is exactly what the average league save percentage was during his career. Given that this was done on losing teams, however, means that his performance was actually pretty good. The average save percentage of his playing partners was .898, and he played with some good goalies, including Arturs Irbe, Ed Belfour, and Jose Theodore. In 12 of his 15 seasons, his team finished in the bottom half of the league in scoring. He also faced an average of 30 shots per game in his career, when throughout most of the 1990s the league average was around 27-28 shots per team. These factors led to a career record of 166-244-56, despite his good performance numbers.

Jeff Hackett was an above-average goalie, and in his prime he was very good. In the four seasons between 1994 and 1998, he posted a .919 save percentage, a 2.24 goals against average, and 14 shutouts in 141 games played on a losing team, and won the starting job away from a potential Hall of Famer. Hackett never received much recognition, however. In his entire career, he only ever received one Vezina vote, a third place vote in 2000. There were better goalies than Jeff Hackett, but he was an underrated, above-average goalie who is an excellent example of a goalie that was overlooked because of the weakness of his teams.