Goalies and Back-to-Backs

So the Flyers have a big pair of back-to-back games this weekend against the Devils and the Rangers, two weeks after playing a back-to-back against the Devils and Bruins. Ilya Bryzgalov started both of those games, and while he had, IMO, one of his best games of the season that Saturday in Jersey, he struggled a bit in the game against Boston en route to a shootout loss. As a whole, though, Bryz is in the middle of a bit of a hot streak; in his last five games he's rocking a 1.74 GAA and .938 save percentage, and the Flyers have nabbed eight of 10 points in those five games.

In the recap comments for last night's game, I posed the question of what you'd do this weekend as far as starting goalies. We can pretty much guarantee Bryz will start at least one of the games, and that's about it. As there usually is here, there were a couple of comments about how it's not a good idea to start goalies back-to-back. There were also a couple of comments about how it's important to try and get him in a groove, and that's also a claim that has been contested in the past and was contested there.

I was, though, a bit more interested in what people think about goalies in back-to-backs. I've seen criticisms of Laviolette in the comments about playing goalies in back-to-back games, both in the scope of (a) how it affects him in the second game of said back-to-back, and (b) how it affects him long-term as the season goes on.

As of now, I don't really have anything concrete for (b), but given that we've got two big games this weekend back-to-back against two (probably) playoff-bound teams, (a) had me a bit curious. Couple that with the fact that there's been no shortage of discussion/complaints about how Peter Laviolette has handled goalies in his two seasons here, and I decided to look into it, in the scope of the Flyers and the league itself this season. Hit the jump.

As of Friday (all numbers are as of before Friday's games), the Flyers as a team had played in eight back-to-back sets of games. They won the first game of each of those back-to-backs in seven of those eight games (every time since the first one, back in October, so that's a good sign for Saturday at least), but only won the second game three times.

In five of those back-to-backs (each of the last five, actually), Laviolette has started the same goalie in both games of the back-to-back five times--Sergei Bobrovsky right after Thanksgiving, and Bryz in the four since then. They've won the first game in all five of those five back-to-backs, but only won the second game twice. So throw a little bit more fuel on that riding-the-hot-hand fire that we know Lavvy roasts his turkeys on.

How's this compare to the rest of the league, then?

(click to enlarge)

A couple quick notes: I only included goalies who started in back-to-back games (didn't count relief appearances) and didn't specify between regulation losses and overtime losses.

As far as individual team results (i.e. the ability to say something like "the Jets' and Penguins' goalies are significantly worse when playing in back-to-backs" or "Mike Smith gains super powers between nights of a back-to-back and this makes his stats better on the back end of them"), we're dealing with an incredibly small sample size on those levels, so we won't look much into that. Heck, the 91-game sample size I'm working off of here is still kind of small. But regardless, here are some notes on that table, on a league-wide level:

--The average team has played in about eight back-to-backs (248 / 30 = 8) at this point in the season, and has sent the same goalie out for both games in about three of them (91 / 30 = 3). On a league-wide level, that means they'll trot out the same goalie in both games 36.69% of the time.
--Only two teams have not once put out the same goalie in back-to-back games: Boston and Florida.
--Of the 28 teams that have done it at least once, seventeen of them have done it with the same goalie every time, and the other 11 have done it with two different goalies at least once. The Flyers, of course, fall into the latter category.
--Goalies and teams perform better in the first game of the back-to-back than they do the second game, winning 52.7% of games and saving 91.92% percent of shots in the first game while only winning 46.2% of games and saving 91.32% of shots in the second game. This is, of course, not surprising at all, because you would think that good performances in the first game would be a big factor in the coach sending out a goalie in the second game.
--With that said, I'm not entirely convinced that teams are leaving themselves worse off (in the short term) starting goalies in a second game, since the league average save percentage this year is 91.32%--exactly the same as the second-game average, down to the fourth decimal place.

What about the Flyers? Well, as you can see there, of all of the teams in the league, only the Senators have put their goalie, Craig Anderson, out for back-to-backs more frequently than the Flyers have. So if you're concerned that Laviolette is working his goalies (namely, Bryzgalov) too hard and it'll make a difference down the stretch, that's what you're going to look at. And based on what we know about how he plays goalies and the fact that the Flyers keep winning the front end of those back-to-backs, it seems possible that he'll keep doing it until it stops working.

So, conclusions:
--Teams play the same goalie back-to-back about 37% of the time.
--When this happens, teams and goalies do well in the first game and typically not as well in the second game.
--However, while a goalie's performance falls off on average, that's more because of his strong performance in the first game. Playing him in the second game makes no difference whatsoever as far as average goalie performance, as it lines up almost perfectly with the league average save percentage. This means that saying something like "Bryz didn't play well because he was on the tail-end of a back-to-back" doesn't hold a lot of weight.
--The effect of playing goalies in lots of back-to-backs long-term is TBD and something I'd have to look into a bit more, but if your team is above that 36.69% mark (which the Flyers are, by a good margin), you may want to monitor the situation a bit more, and/or get a better backup goalie. Since the Flyers obviously have no problems with their backup goalie, maybe Laviolette should give Bob a game this weekend, no matter how good Bryz has been recently.