clock menu more-arrow no yes mobile

Filed under:

Goalies on back-to-backs, or why Steve Mason should start tonight's game against the Maple Leafs

Not that this is shocking, but goalies don't do well in net when they're playing back-to-back games. Should Peter Laviolette be giving Ilya Bryzgalov's new backup tonight's game?


NOTE: Again, the Flyers manage to circumvent something I write by beating me to it before I publish. This was originally written about how Michael Leighton has to play eventually and is now about how Steve Mason has to, at the very least, play today.

NOTE #2: Ilya Bryzgalov is starting tonight. I am shocked to learn that Peter Laviolette does not read this website.

One night after an excellent win on Wednesday night against the Canadiens, the Flyers will play the second half of a back-to-back contest tonight, facing off with the Canadiens hop on over to Toronto for a game against the Maple Leafs.

Ilya Bryzgalov started last night's game, and it was his 21st (!) consecutive start for the Flyers. In those 21 games, Bryz has played every single minute of 19 of them, and was replaced mid-game by Brian Boucher (who, of course, isn't even on the NHL team right now) in the other two. Over the course of the entire 36-game season so far, there have only been five games that Bryz did not play from start to finish.

While those are some pretty absurd numbers -- and while our own Eric T. has already debunked the myth here that goalies need to keep playing to get in a good rhythm -- I get why Peter Laviolette feels that he should be playing his best goaltender every chance he gets. Bryz is obviously a better goalie than Boosh or Michael Leighton (and, even though he's probably an improvement over both of those guys, Steve Mason), and with this team still somehow in the playoff race, you may as well play him as much as is reasonable.

But there's a limit. Today marks the Flyers' ninth set of back-to-back games so far this season. Of the eight prior, Bryz got the start in both games of six of them. I'm not going to look too much into Bryz's particular results in those games, because fourteen or however many games is hardly a definitive enough sample size, but a look at goalies around the league can tell you that by continuously sending out his best goalie on back-to-backs almost every time, Laviolette is not helping his team win.

The table below cumulates the save percentages of every goalie appearance in the 2013 NHL season (through April 1) that came on any given number of days of rest, along with the total number of appearances for each count. I grouped everything greater than five together because after that the samples are small for each number of days. Take a look:

Days Between Appearances Count Save %
0 95 0.892
1 461 0.913
2 205 0.91
3 95 0.911
4 64 0.914
5+ 151 0.910

Or, if you prefer graphs:


(Note: each goalie's first appearance of the season is excluded from this data because obviously that's a lot more rest than we can quantify here.)

If you look there, the one thing that obviously sticks out is the giant jump from zero days of rest to one. For the most part, once you get past that initial day the results aren't that far off between any given two amounts. All neatly packed between .910 and .914.

But the difference between performance in back-to-back appearances and even one day off is not only noticeable, it's staggering. In 95 appearances this year on the tail end of consecutive appearances, goalies are only stopping 89.2% of shots. In all other situations combined, that number is 91.2%. That's a 2% drop, which is huge, and while the sample isn't that big here, (a) I think this (goalies don't do well when asked to play on consecutive days) is relatively sensical, and (b) the difference is large enough that we can probably assume this isn't just noise.

So what's the point? Yes, Ilya Bryzgalov (a career .914 goaltender) is much better than Mason is (.903) or than Leighton was (.901), but the difference in performance there is outstripped by the difference in goaltending quality as a whole when guys are forced to play on the tail end of back-to-backs. If we apply that 2% drop to Ilya Bryzgalov, his expected save percentage dips to .894, meaning the benefits otherwise of playing him over Mason or whoever are probably overshadowed by the fatigue factor.

The Flyers only have two more games on the back end of back-to-backs this season -- the current one, and one on April 16. If that means that Steve Mason only gets two starts in orange and black this year, I can live with that. But trotting Bryz out for all of those games, particularly the tail end of back-to-backs, is hampering this team's chances to win hockey games.

But hopefully Peter Laviolette realized this and that's why they traded for a backup slightly less bad than their old one.