Sunday, October 25, 2009

The Effect of Back to Back Games II

In January of last year I looked at the effect of playing a game as the second half of a back-to-back on the road as opposed to playing a regular road game. I began by wondering if there is a real effect on teams playing back-to-back games and if there is, just how significant it is. I've now finished gathering the data from last year and am happy to present that data now.

I have now checked every game where the team on the road is playing their second game in two nights, regardless of whether the first game was at home or on the road. Last season there were 316 such instances out of 1230 total league games. That means 25.7% of games involve the road team playing its second game in two nights! If there is a significant disadvantage to playing back-to-back games this might help explain some of why teams perform better at home than on the road (teams play some second half of back-to-backs at home, but the number is much smaller).

So how did road teams do in this situation? Well, after taking out shoot-out goals, the goal differential of the road team is -158 or -0.50 goals per game. The points percentage of the road team in this situation is 0.470 and the winning percentage of the road team in this situation is 0.410. In the other 914 road games the visiting team had a points percentage of 0.506 and a winning percentage of 0.452. That's a massive difference!

Still, the biggest difference is likely in inflating home records and deflating road records which keeps fans happy and makes people believe home-ice advantage is bigger than it really is in the playoffs. But it probably doesn't create a huge gap in the standings since most teams play about the same number of back-to-back games on the road and each extra road back-to-back only ends up being worth about 0.08 standings points. The biggest gap in the Eastern Conference was between the Pittsburgh Penguins who played four of these road back-to-backs and the Buffalo Sabres who played fourteen for a difference of 0.80 standings points. In the West the biggest gap was between the Colorado Avalanche who played five and the Detroit Red Wings who played sixteen for a difference of 0.88 standings points. Still, in a league where many teams adjust their playoff seeding on the basis of only one or two points, it's a part of the scheduling process that teams need to look at closely. Every little bit counts.

4 comments:

Dennis said...

I guess I sort of instinctly knew this anyway but it's a good tool to use for betting:)

Scott Reynolds said...

It sure is. I know bookies tend not to be stupid so they probably factor it in on the line but it's still something to keep in mind if you're putting money on the line. Also worth knowing: the bad teams tend to get kicked by this worse than the good ones.

JLikens said...

"It sure is. I know bookies tend not to be stupid so they probably factor it in on the line but it's still something to keep in mind if you're putting money on the line. Also worth knowing: the bad teams tend to get kicked by this worse than the good ones."

I remember Chris at hockeynumbers mentioning this when he did his own study on this very topic a while back.

I find this to be interesting, although I'm sure why the effect varies as a function of team strength.

Scott Reynolds said...

Oh crap, I got it backwards; it's the good teams that tend to get kicked more by this than the bad ones. Or given the results JLikens mentions, maybe it's random. I hope I didn't cost you any money tonight Dennis :)

Teams with a pts% of .575 or better in non-back-to-back road games totaled .616. That fell to .482 in the back half games.

Teams with a pts% between .500 and .574 in non-back-to-back road games totaled .541. That fell to .485 in the back half games.

Teams with a pts% between .426 and .499 in non-back-to-back road games totaled .462. That increased to .481 in the back half games.

Teams with a pts% of .425 or less in non-back-to-back road games totaled .400. That fell to .355 in the back half games.