Sunday, March 13, 2011

The Capitals Defense

Much has been made about the Capitals trying to play better defense this season, as the offense stopped coming in droves in December and the system had failed the Capitals in the playoffs.

In my mind, there are several ways to look at defense:

  • Goals against. Over the long run, we'd expect this number to be most indicative of a team's defensive prowess (obviously), but in the sample size of 82 games, it's subject to goalie hot/cold streaks, luck on special teams, and so forth.
  • Shots against. Give up less shots, you'll give up fewer goals. Obviously, not all shots are created equal, but if you're a team that significantly reduces shots against (like St. Louis or Chicago) then the effect is greater than reducing quality (which has an inverse relationship with quantity--decrease quality, increase quantity).
  • Fenwick events against.
  • Corsi events against. While goals and shots against are more indicative in the long run, the much larger samples Fenwick and Corsi provide increase the confidence we can have in the ratios in the short run.
  • The for-against differentials of these metrics, rather than pure "against." Does it really matter if you give up 3 goals a game if you score 5? It's high-risk, high-reward (a tradeoff that was probably perfected by the dynastic Oilers).

2010-2011 obj nhl is from here. Data pre-PIT SOL is from here. 2007-2010 numbers are from these links. I added up the numbers from Timeonice single game Corsi charts to get the data from late February onward.

That increase of about 2 shots per game, at a .920 save percentage, would result in 13 extra goals against over an entire season. The Caps are on pace to allow 44 power play goals, down from 67 in 2009-2010, 75 in 2008-2009, and 68 in 2007-2008.

What's changed from then until now? A combination of the following factors:
  • Teams trying more and more to prevent the Capitals from opening up the transition game. From the behind the net link below, you can see the Capitals, as soon as the score changed from tied, got leaps and bounds much better (from pedestrian with score tied to 2nd best down 2). They thrive when the game opens up (either by the other team being forced to attack aggressively, or not really attacking while trying to defend a lead).
  • The loss of Sergei Fedorov, who was an absolutely dominant 2C.
  • More balance in the lineup. Mike Green no longer gets below average competition with 60% zone starts, for example, and even the top line's quality of competition has been creeping up this season to about 0.400 (still last on the team, but a far cry from years past). The minutes are distributed more evenly, as if Bruce Boudreau is taking less notice of matchups. I like power versus power, but the best team this year and last both went with the "comparative advantage" strategy, giving their (supposed) best defensive players all the hardest situations and giving every offensive zone draw to someone competent offensively (which unfortunately Bruce Boudreau cannot do).
  • A decline from Fehr/Flash. Tomas Fleischmann in 07-08 was actually pretty good, and when he faltered the next season, Eric Fehr picked up the slack in a huge way. No other "tertiary" player has picked up the slack since--Brooks Laich and Alexander Semin have, but probably at the expense of some offense. "Tertiary" players handling harder minutes leaves prime scoring minutes for the top-6 forwards.
  • Alex Ovechkin's uninspired play for much of this season and the latter part of last season.
  • Bruce Boudreau probably increased the team's shot blocking skill with the system change. I think that's in part because a less aggressive forecheck neutral zone coverage scheme allows for easier offensive zone entries for the opponent.
Though this team is better defensively than I'd thought, there's still no doubt in my mind that, while Alex Ovechkin may yet be in the running for the Hart, that special trio of goalies are the guys keeping the Caps in the running at this point. Score effects aren't the only reason the Caps are winning despite allowing more Fenwick and Corsi events per game--it's the .942 'tending.

Leading into today's matinee with the defending champs, well, something tells me the Caps will need to find some comeback juices and have a good day on the power play. At the very least, it's not like they're bad at that.

With the playoffs approaching...I hope the goalies can put up a hot streak.

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