Wednesday, 30 May 2012

Devils/Kings Stanley Cup Final Preview: Analyzing the finalists through stat nerd goggles

Leading up to Wednesday's Game 1, Puck Daddy is previewing every facet of the Stanley Cup Finals between the New Jersey Devils and the Los Angeles Kings— on the ice and off the ice.

To say that the 2011-12 Stanley Cup Final between the Los Angeles Kings versus the New Jersey Devils was predicted by advanced analysis would be folly — even the most ardent hockey modeler couldn't have forecasted this outcome with any sort of certainty.

It would be closer to the truth to say that those paying attention to the underlying numbers are less surprised by this match-up than most: The Kings and Devils haven't had the best records over the last season or two, but their true talent level was probably higher than their records indicated.

We'll start with the Kings.

They might be the best eighth seed the league has seen since the lockout.

Their position in the standings was deceptive for a couple of reasons — first, a couple of mid-season changes that altered the team for the better and second a ghastly even strength shooting percentage that was unlikely to continue.

Under Terry Murray, Los Angeles was a capable enough squad in terms of controlling the play and getting shots on net. Through the first 32 games, they outshot the bad guys 326-305 (51.6 percent) with the score tied. Their overall shots at the net ratio (or corsi) was 51.4 percent at the time (again with the score tied, which eliminates score effects). Unfortunately, they also suffered from the lowest even strength shooting percentage in the league — around six percent.

The mean ES SH percentage in the NHL usually hovers around 8 percent. That doesn't sound like much, but over hundreds and hundreds of shots, a couple of percentage points makes a huge difference. For further context, only one or two clubs per season manage a five-on-five shooting percentage of less than 7 percent.

So the Kings couldn't score and Murray was replaced by former Flames savior (and destroyer) Darryl Sutter.  The Kings SH percentage continued to be lousy (although it improved marginally) but the real difference was in shot volume — over the final 49 games, LA outshot the bad guys 554 to 412 with the score tied (57.6 percent). They finished the year under Sutter with the one of the best possession rates in the league (57.8), which was one of the biggest in-season swings in recent memory (Dan Bylsma did something similar for the Penguins when he was hired a few years ago).

Of course, Sutter was further aided by the Jeff Carter and Jack Johnson trade. That swap helped LA in both directions — Carter arrived and managed a 60.7 corsi-tied ratio with the Kings in 14 games played, which is elite territory — while losing Jack Johnson aided possession numbers from the back-end.

Although he's well known as a capable offensive contributor, the truth is Johnson has been lousy at driving the play since he broke into the league and tends to be a liability overall.

In 2010-11, for instance, his corsi rate of minus-2.39 per 60 minutes of ice was the worst amongst LA blueliners even though he started his shifts more often in the offensive zone (51.5 percent). Through the first 32 games under Murray, Johnson's corsi-tied ratio was abysmal (45.4 percent). In fact, he was again the worst defender on the team by this measure at the time.

The combination of the Sutter improvement, the addition of Carter and the subtraction of Johnson made the Kings a possession monster heading into the playoffs. By March 27, Eric T of Broad Street Hockey showed the Kings as the best team in the league by possession metrics. LA was winning despite an NHL low shooting percentage, so heading into the post-season it didn't take much imagination to wonder how they would do with even an average SH percentage...

The New Jersey Turnaround

The Devils' reversal of fortunes is tied to scoring rate as well.

Lucky Lou's club famously fell on their face in 2010-11, thanks in no small part to a similarly poor even strength shooting percentage — 6.7 percent. New Jersey was the only team in the league to score on less than 7 percent of their shots on net at five-on-five that year.

In fact, 24 of the 30 clubs scored at 8 percent or better.

Unfortunately for the Devils, they had neither a sudden, step-wise improvement in possession part way through the year, nor Jonathan Quick's Vezina caliber season to save them from the basement. They finished 11th in the East and 23rd in the league.

Like the Kings, however, the Devils weren't a true basement dweller. They outshot their opponents on average and only a poor SH percentage (mixed with some mediocre goaltending) kept them from competing.

The dirty little secret about yearly shooting percentage in the NHL: It says almost nothing about the true talent level of a team.

The percentages tend to regress towards the mean over time. This is something you can check by looking at each club's even strength SH percent and rank each year.

For example, the Devils were last in the league in 2010-11 (6.7 percent) and 13th this season (8.5 percent). The Kings were last in the league this season (6.4 percent), but 10th overall the year prior. The most efficient team at five-on-five in 2011-12, Tampa Bay (9.9 percent), was only 16th overall in 2010-11.

This more or less random fluctuation in team shooting percentage plays out pretty consistently season-to-season. Back in November, Jonathan Willis looked at each team's even-strength shooting percentage from 2007-2011 to see if there was any correlation from one year to the next.

The average correlation overall was minus-0.003 (meaning there was no relationship). In fact, he found that the average finish for the top rated team in one season was 14th overall the next. Clearly, variance and randomness plays a large part in a team's SH percent rank, and a lousy goal rate, doled out by lady luck, can play nevertheless havoc with a club's record.

As such, the Devils were an excellent candidate to bounce back in 2011-12. And indeed they did — enough to make it into this year's wacky post-season and ping-pong their way to the cup finals.

Final Word

Anyone who tells you they can accurately predict the playoffs is either a fool or a shyster, so the LAK-NJD final could not have been divined by any collection of stats, be it conventional or otherwise.

However, there were some indications prior to this match-up that both clubs were better than most would have expected.



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