Tom Poti: The Key To The Kill?

On their recent swing through Florida the Capitals did a lot of things right.  Most of them - significant offensive output, timely goaltending, a strong powerplay, contributions from rookies - were nothing new for this season. 

One notable exception (and a pleasant surprise indeed) was the team's penalty kill which, despite being in the bottom third of the league in terms of effectiveness at 80.1%, killed eleven of twelve penalties in the back-to-back games, including eight of nine against the Lightning on Saturday night.  Of course, neither the Lightning nor the Panthers exactly set the world on fire when it comes to powerplay effectiveness, but it was no doubt an encouraging showing for a team that has struggled shorthanded for most of the season.  And right at the center of the Capitals' penalty kill unit was Tom Poti who, with 4:38 of penalty kill against Tampa Bay and 7:02 of penalty kill time against Florida, led all Caps player in shorthanded time on ice in each game.

The team's road trip to Florida served as a microcosm of Poti's impact since his return to the lineup.  In the fifteen games Poti missed between December 23rd and January 27th, the Capitals killed only 75% (48 of 64) of the shorthanded chances they faced and had allowed at least one powerplay goal in eight straight games (half of which saw them concede more than one goal while a man (or two) short).  Since Poti's return to the lineup on January 31st, however, the Capitals have killed 88.8% (40 of 45) of their penalties, have allowed powerplay goals in just five of their eight games, and have yet to allow more than one on a single night,.

The marked difference between the performance of the team's powerplay with Poti in the lineup got me wondering just how big the defenseman's impact has been this season.  Here's what I found:

Simply put, Capitals win more games, against better opponents, by bigger margins with Tom Poti in the lineup.  The difference in quality of opponents was significant enough that it drove me to crunch the numbers and find out how teams were performing against the Capitals relative to their overall season performance.  The comparison, for games without Poti in the lineup:

And for games with Poti in the lineup:

Finally, to wrap things up, here's how the Capitals' opposition has deviated from their season averages, by percentage, playing against the Caps with and without Tom Poti in the lineup:

Now, any statistician or economist worth his salt will tell you that correlation does not necessarily equal causation, and that is of course the case here.  As result it's hard to say anything definitive about Poti's impact on the Capitals lineup, but that doesn't mean we can't say what the numbers suggest: without Tom Poti in the lineup, the Capitals are a good team.  With him in the lineup, they are simply dominant.

[Ed. note: Because of all the number crunching that had to be done for this post, team statistics are current through February 16th. Additionally, for the purposes of this discussion winning percentage is defnined as the number of standings points a team accumulated divided by the number of possible standings points.]