Round 2 Preview and Round 1 Review

The second round of the Stanley Cup playoffs begin tonight (in 37 minutes at the moment I started writing this, to be precise), and after an exciting first round it’s nice not to have to wait even one night to get back into the action. In the first round our model had a good showing, correctly predicting the winners of 5 of 8 series while missing on the Avs (incredibly high shooting percentage), Lightning (replacement level backup playing for Vezina candidate) and Blue Jackets (not really clear that either team was trying to win the series).

While some might not view 5 of 8 as a great percentage, from the point of view of the model it was actually spot on. Since our model picks not only the winners but also the probability of each team winning, we have to look at the predictions it makes in the context of each team’s predicted winning percentage. After all, the model was much more confident in its pick of Anaheim (71.8%) than of Columbus (53.6%). Because our predicted win probabilities aren’t 100%, we shouldn’t get all of the series right and we should actually be worried if it does: if we’re able to consistently pick all of the winners even if we don’t view them as 100% favourites it means that our model is actually underestimating the probability, and not giving us a good view of each team’s odds.

To illustrate this further, imagine we predicted 5 series: in 3 of them we predicted that the favourite would win 66% of the time (2 out of 3 times), while in the other two we viewed each team as having equal odds (50%). In this world we’d expect to get 3 games right: 2 of the 3 66% series, and 1 of the two coin flips. We can get an estimate of how many games we think we should get right by simply adding up the probability of the favourites (0.66 + 0.66 + 0.66 + 0.5 + 0.5 = 3)

Looking back at our model, we can estimate how many series we should have predicted correctly by applying a similar analysis. Using our round 1 odds for all of our favourites our expected number of correct predictions is: 0.685 + 0.556 + 0.536 + 0.594 + 0.634 + 0.635 + 0.718 + 0.549 = 4.91. So when we got 5/8 right, we’re actually right around where we’d expect to be (admittedly due to the  small sample size we won’t always be that close, but you get the point).

All of which is to say that the model did a pretty good job at round 1, perhaps better than it would appear at first glance. With that beings said, let’s take a look at what we expect to happen in Round 2.

Looking at the numbers, if you’re a fan of the exciting, close series we saw in round 1 you’re likely in for a bit of a disappoint. Both Boston and Chicago are viewed as overwhelming favourites by the model, with each team coming in above 80% to move on to the conference finals. Unsurprisingly, the Hawks and Bruins are also heavy favourites to take home the Cup at this point, with the model seeing only a 34% chance that Lord Stanley’s mug won’t end up in Beantown or the Windy City.

The only other team with a decent shot at the cup, at least according to our predictions, are the Anaheim Ducks, who enter their series against the comeback Kings as 63% favourites. Los Angeles obviously cares not for the rules of probability though, as they were down to 8% odds to move on and less than 1% to win the cup after losing 3 straight to start their series with the Sharks. While the Ducks struggled at times versus the Stars, the model still favours their high shooting percentage game over the pure volume effort that the Kings tend to put forward.

The closest series, and the one this author is most excited for, is the Penguins-Rangers series set to start tomorrow in Pittsburgh. While the Pens definitely struggled at times in their series versus Columbus, and while Marc-Andre Fleury has done little to combat his reputation for choking in the clutch (not that clutch play is really a thing, but that’s another story) the team led by the Cole Harbour Kid enters their series as slight favourites over the Blue Shirts. Similar to the Ducks-Kings series this looks to be another quality versus quantity matchup, with the Pens relying on Sid the Kid and Evgeni Malkin to drag their woeful bottom 6 past New York’s Fenwick machine (oh and perhaps the greatest goalie of his generation, Henrik Lundqvist).

Coming back to our little probability exercise that we started with, let’s take a look at how many series we expect the model to get right this round. Taking the expected win probabilities of the Bruins, Penguins, Ducks and Blackhawks we should get approximately 2.8 series correct, or roughly all but 1. So there you have it: you’re now prepped for Round 2, and there’s actually still time left to grab a beer before the anthem!