Thursday, April 15, 2010

Rookies vs. Veterans

Day one of the playoffs is in the books, and the big stories were upsets and playoff rookies doing well. Playoff newcomer Brian Elliott outplayed defending Champ Marc-Andre Fleury while Craig Anderson also won in his first taste of NHL playoff action.

Experience usually gets a lot of play in the media and around the barstools at this time of year. From a goalie perspective, there is a noticeable lack of experience among most of the playoff teams this year. Seven goalies will be making their playoff debuts, while another has just one start to his name and yet another has just one start in the last 10 years. Here are the career playoff games played prior to last night of the 16 expected playoff starters:

1. Martin Brodeur, 176
2. Evgeni Nabokov, 65
3. Jose Theodore, 49
3. Marc-Andre Fleury, 49
5. Ryan Miller, 34
6. Roberto Luongo, 22
7. Brian Boucher, 22
8. Ilya Bryzgalov, 16
9. Jaroslav Halak, 3
10. Pekka Rinne, 0
10. Jimmy Howard, 0
10. Jon Quick, 0
10. Craig Anderson, 0
10. Antti Niemi, 0
10. Tuukka Rask, 0
10. Brian Elliott, 0

Does that mean that New Jersey, San Jose or Pittsburgh are the most likely teams to win the Cup? Not in my book. There has not been much of a relationship between goalie experience and playoff performance, suggesting that experience is largely overrated as a factor in postseason success.

Since the lockout, here are the numbers for goalies in their first playoff season compared to the numbers for goalies who had prior playoff experience (goalies with less than 120 minutes of prior experience were still counted as rookies):

Veterans: 244-230, 2.46, .914
Rookies: 92-106, 2.58, .913

The save percentages for the two groups were essentially identical. It is even closer than the rounding makes it appear. The rookies were at .9134 while the veterans were at .9136, a difference of .0002 over a total sample size for both groups combined of over 20,000 shots. Assuming that differential represents the true skill difference from having been there before, experience would seem to account for one additional goal saved every 24 playoff series. That's one goal every 6 playoff seasons if the goalie's team went to the Finals in each and every one of them.

The rookies faced an extra 1.4 shots against per game, which accounts for the difference in GAA and likely much of the difference in win/loss record. It seems unlikely that the goaltenders in either group would have had an effect on the shots against, since the sample is made up of a diverse group of athletes and the goalies who made their playoff debuts between 2006 and 2008 appear in both samples. The most probable explanation is that the best teams in this period tended to have playoff veterans. This is supported by the fact that although several goalies had great performances in their first playoff seasons, the only one to make it to the Finals was Cam Ward in 2006.

Last night the rookies combined for a .902 save percentage while the veterans combined for .910. The main reason for the veterans' slight outperformance was Brian Boucher, a guy who played a total of two minutes in the playoffs from 2003 to 2009. Three of the five most experienced playoff goalies were in action last night, and those veterans combined for a dreadful .871 save percentage.

When a rookie goalie gets shelled, people usually make up stories about how he lacked experience and couldn't handle the pressure. When a veteran goalie who has won before plays poorly, it usually gets attributed to other factors (fatigue, the team in front of them, old age, etc.). The excessive focus by many on playoff experience appears to mostly be caused by confirmation bias. People only remember the data points that fit the sample. If you look at the entire sample in recent years, there is essentially nothing at all to suggest that a playoff newcomer will perform worse than a grizzled veteran.

Calling a goalie a playoff rookie in the first place is often a very NHL-centric view, especially with an ever-increasing crop of Europeans coming over to play goal in North America. Most of the netminders with zeroes beside their names above have extensive playoff experience in Europe, the AHL or international competition. The only two starters with essentially no playoff experience as a professional are Elliott and Quick, and they both played in the NCAA Championship.

If you want to predict playoff goalie performance, I don't think you'll lose much accuracy at all by focusing on a goalie's talent and regular season track record and ignoring the variable of experience.


Kent W. said...

This is probably the case for skaters as well. Take the Flames for example: their best playoff run in the last 20 years occurred when the entire team was essentially green.

Glen Sather Sucks said...

this should be required reading for every "mainstream" hockey writer or analyst who points to a goaltender's experience as a likely determining factor in a series.

Anonymous said...

Patrick Roy > Martin Brodeur

uvgt2bkdnme said...

Maybe not now, but this should definitely go in the "Best Posts" section.

Anonymous said...

Still a fan of 8uongo's? :-)

Derick said...

There's about 90 total playoff games ever, mostly from Nabokov (9) and Miller (4), in the top 10 and about 200 in the bottom 10, with Brodeur, Fleury, Luongo, and Theodore in the bottom 10. The top three goalies have all never played a playoff game.

Anonymous said...

Anonymous said...

Ugh, the link isn't working, but it's an ESPN list of goalies who have played these playoffs, by save percentage. There's exactly 20.