Momentum plays real and important role in post-season

In 16 NHL cities that aren’t Toronto, much of the talk over the past few weeks has been about the “momentum” each team carries into the playoffs.

During lulls in the game when colour commentators are desperate for something passably intelligent to say, they trot out the good ol’ clichés about how either their club’s strong close to the regular season could be the ticket to post-season glory, or how the team’s stumble to the finish line spells disaster for the second season.

Ordinarily our reactions to trite explanations like these range somewhere between Phil rolling his eyes and IJay wanting to rip off his own ears so he doesn’t have to listen any more (yes, he recognizes that muting the TV would be a less melodramatic solution).

But when it comes to team momentum going into the playoffs, the Department of Hockey Analytics thought there might actually be a kernel of truth in this platitude.

It makes sense that a team’s performance right before the playoffs might be more meaningful than the team’s performance earlier in the year for various reasons.

A struggling team might have important injuries that carry over into the playoffs or a surging team might have gotten healthy.

Maybe a team finally managed to sort out its defensive systems or line combos.

Or maybe players just happened to be riding a natural performance peak — like a runner or swimmer who carefully manages her training so her performance peaks right at the Olympics.

To test the theory, for every playoff series since 1998 we determined each team’s probability of winning as a function of the regular-season point differential between the two teams and their relative “momentum” coming into the playoffs. We measured momentum by the points each team earned in (a) the last five games of the regular season and (b) the last 10 games of the regular season.

The results are shown in the graph. Each dot represents a single team in a single first round series. The location of each dot reflects the probability that the team would capture the series as determined by our model.

As expected, the team with more regular season points was more likely to win each series.

While that’s hardly newsworthy, we were able to quantify just how much it mattered.

For each extra point a team had over its playoff opponent, it was, on average, one per cent more likely to win the series.

For example, all else equal, a team with 10 more points than its opponent stood about a 60 per cent chance of moving to the next round. There was also a fairly strong relationship between performance over the last 10 games of the regular season and the likely outcome of the first round of the playoffs. In fact, a single point of difference over the last 10 games meant a 2.2 per cent increase in the likelihood of winning the series — or more than twice as powerful a predictor of playoff success as a point difference over the entire regular season. So the probability that the team with the 10-point regular season edge would win the series shrinks from 60 per cent to 55.6 per cent if its opponent earned just two more points than it did over the last 10 games. However, momentum over just the last five games of the season doesn’t seem to matter. Why do the last 10 games matter but not the last five? That’s hard to say. Possibly because, in the last five games, teams that have locked up a playoff spot start resting their players, or maybe five games is just too small a sample size to be meaningful. What does all this mean? First, since there seems to be no correlation between a team’s performance over the last five games and its playoff performance, it means teams should be less concerned about a little rust at the start of the playoffs and should freely rest their players as the season comes to its conclusion.

Second, as far this year’s first round matchups are concerned, in the Eastern Conference it means that the Rangers might be more of a favourite than their two-point regular season lead over the Flyers indicates due to their superior record over the last 10 games (6-2-2 versus 4-3-3).

In the West, it means that despite the Blues’ late season implosion, their series with the Blackhawks still promises to be a close one, since the Blackhawks had the secondworst record of all playoff teams over the last 10 games.

The Department of Hockey Analytics employs advanced statistical methods and innovative approaches to better understand the game of hockey. Its three founders are Ian Cooper, a lawyer, former player agent and Wharton Business School graduate; Dr. Phil Curry, a professor of economics at the University of Waterloo; and IJay Palansky, a litigator in Washington, D.C., former high-stakes professional poker player and Harvard Law School graduate.