One of the most enjoyable aspects of the current 5-0-1 run that the Nashville Predators are on is an unexpected surge in goal-scoring, which is coming from all four of the forward lines. Ryan Jones is working a 4-game streak, Patric Hornqvist reached double-digits with two goals in Edmonton last night, and both Martin Erat and Steve Sullivan have achieved hat tricks in recent days. Even Jerred Smithson and Joel Ward scored as well.
After trouncing the Tampa Bay Lightning 7-4 at home Tuesday night, John Glennon started the post-game press conference by asking Barry Trotz if the team had transformed into an offensive dynamo. Trotz replied with a deadpan "No", for of course he doesn't want anybody to lose sight of the lunch-bucket mentality that is the hallmark of his coaching style.
But the question remains - how much of this current scoring trend is sustainable? Let's take a look...
The tool I'm going to use to dig into this question is called Shot Quality; the notion that each shot can be assigned a value between 0 and 1, which represents the chance that a shot of that type will result in a goal. The factors I'm using here are the distance from the net, the shot type (slap, wrist, backhand, etc.) and whether or not it is a rebound attempt.
For example, a wrist shot from between 10 and 20 feet out might have a 14% chance of resulting in a goal on a normal attempt, but if it's a rebound opportunity, that value jumps to 34%. If you sum up all the Shot Quality values for a given game, you get an Expected Goals figure, which reflects how many goals you should score based on average goaltending.
I'm also using only Even Strength play here, setting special teams aside for the moment.
Since 80% or so of an NHL game is spent at Even Strength, my question here is how many goals the Preds should be scoring, and how the bounces of any given game have worked out.
The graph below shows the actual Even Strength goals scored per game (in red), and the Expected Goals (in blue). The game numbers below the horizontal axis are the game ID's from NHL.com. As an example, last night in Edmonton the Preds scored 5 goals at Even Strength, but based on the total of Shot Quality, they should only have Expected to score 2.25.
So what does this tell us?
Preds finally getting a break
The first thing to note is that the last 9 games (starting with a 5-4 overtime loss at Minnesota) are the first stretch that has seen the Actual Goals exceed the Expected Goals for any length of time, with a difference of +14.33 total goals; in other words, the bounces are finally going their way. That makes up for the first 22 games of the season, which saw the Preds score 14.5 goals less than Expected. In the 35 games to date, they've scored 1.91 goals less than Expected at Even Strength, which isn't a significant deviation for the overall total.
Basically, this hot streak lately has balanced out some snake-bitten games early on (recall the 1-0 loss to Buffalo, for example). This tells us that we shouldn't bank on the guys earning Frosties for the fans again any time soon, as a good chunk of this recent production is simply a matter of luck.
These aren't last season's Predators
The good news, however, is that this team is generating scoring opportunities at a decent pace, and if the goaltending and team defense hold up, the Predators should be able to keep up an above-average Goals For/Against performance.
To date this season, the Preds are generating 2.11 Expected Goals per Game at Even Strength, good for 7th in the NHL. In 2008-9, that figure was just 1.83, which ranked 22nd. Thanks in large part to the return of Steve Sullivan and production outside the Top Six by guys like Hornqvist and Jones, the Preds are a significantly better offensive team this time around.
Just to repeat, I'm looking only at Even Strength activity here; special teams warrant their own analysis, which will await another day. Also, the Shot Quality model I'm using is relatively crude compared to the latest tweaks discussed over at HockeyAnalytics.com (PDF). I'm just starting to get this stuff into database form where I can do this kind of analysis, and hope to flesh it out more thoroughly as the season progresses.
That said, this provides a more nuanced view of offensive performance than merely looking at shot totals.