Jan 122012
 

There is a post over at Backhand Shelf today that lists 10 backup goalies that have out performed their #1 counterparts.  It is an interesting read but it may be a perfect example of how simple statistics don’t tell the whole story.

The first pair of goalies on the list are the Bruins Tukka Rask vs Tim Thomas.

Backup: Tuukka Rask (10-4-1, 1.59 GAA, .945 SV%)
Starter: Tim Thomas (17-7-0, 1.99 GAA, .938 SV%)

Now both goalies have exceptionally good numbers but on the surface you would probably conclude that Rask has superior numbers to Thomas and on the surface you would be correct.  But dig a little deeper and things may look a little different.

A few days ago I was wading through some statistics and made an interesting observation about the Bruins handling of these two goalies.  Specifically, Tukka Rask gets far easier starts than Tim Thomas.

Rask Thomas
Opp. Record 265-257-72 511-418-123
Opp. Points % 1.013 1.088
Opp. Points/82gms 83.1 89.2
Opp GFA 2.55 2.77
Opp Sh% 8.66% 9.29%

Thomas’s opponents have a better record, have a better goal scoring rate and have a better shooting percentage than Rask’s and generally speaking it isn’t very close.  Boston has the highest goals per game average in the NHL.  The next 6 teams are Philadelphia, Vancouver, Detroit, Toronto, Chicago and Ottawa.  Of Rask’s 14 starts he has 2 starts (14.3%) against those six teams, one against Toronto and one against Detroit.  Thomas has 25 starts, and 9 starts (36%) against those six teams (3 vs Toronto, 2 vs Ottawa, 2 vs Philadelphia, 1 vs Chicago and 1 vs Vancouver).

When you take Rask and Thomas’s individual numbers on the surface it appears that Rask has out performed Thomas but when you dig deeper and look at the quality of opposition it is far less clear that Rask has outperformed Thomas and in fact it may be the other way around.

(On a side note, the combined record of all of Boston’s opponents is just 776-675-195, the equivalent of an 87 point team so it seems they have had a fairly easy schedule thus far. )

 

  4 Responses to “Tim Thomas vs Tuukka Rask”

  1.  

    I did a piece on Miikka Kiprusoff for Hockey Prospectus just over a year ago, and as part of that study took a look at the difference in even-strength save percentage between each goalie and their team’s alternatives.

    http://www.hockeyprospectus.com/article.php?articleid=714

    Kiprusoff outperformed his back-up by the widest margin, followed by Henrik Lundqvist, Ryan Miller, Roberto Luongo and Marty Turco. Remember this is post lock-out and was done a year ago.

    I’ve still got the raw data somewhere, I’ll see if I can find it and dig up a list of back-ups that consistently out-perform their starters.

  2.  

    Hi David, if you adjust the save percentages for shot quality, does Rask still outperform Thomas? Shouldn’t that settle the matter definitively?

    •  

      Rask: 94.5% save percentage is a 5.5% shooting percnetage against, or 3.16% below opposition team averages.

      Thomas: 93.8% save percentage is a 6.2% shooting percentage gainst, or 3.09% below opposition team average.

      So, Rask is still marginally better though it far too close to say conclusively since we haven’t taken into account PP/SH time, score effects, etc.

      The point is, I am not certain Rask has out performed and I suspect Tim Thomas is a marginally better goalie, but both are really good and both benefit from a tight defensive system.

      •  

        Thanks for clarifying David. Any idea, in general, how much explanatory power (of a teams record) goalie performance has?

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