August 21 2012 06:53PM
By goaliej54 [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
The Bruins enter 2012-13 season with largely the same roster for the third year in a row. There have been some small tweaks here and there, replacing Tomas Kaberle with Joe Corvo and letting Tyler Seguin grow into Mark Recchi's minutes, but the core has largely remained intact.
With one notable exception.
How critical has Tim Thomas been to their recent success? What should we expect from the team going forwards?
The plot above (explained here) shows that their top two lines faced virtually identical opponents -- all six players saw very similar opposing defenses and forwards, as the team's depth ensured that all of them got a bit of time against the opposing second and third pairings. That undoubtedly helped Seguin, who didn't have the very best sophomore season ever, but is in pretty lofty company nonetheless.
The Bruins probably got a bit lucky this year, as they ranked second in the league in 5-on-5 shooting percentage. New readers might be wondering why I assume that has to involve luck; I'll give three different answers.
The first answer is theoretical: a year seems like a long time, but when you're trying to tell the difference between 9.4% shooting and 8.8% shooting, 2000 shots isn't nearly enough for random bounces to even out (it's a difference of just 12 goals). The second answer is semi-practical: we've seen that the spread between teams in shooting percentage is pretty close to what you'd get by random chance even if every team had the same talent. And finally, a purely empirical answer: with a very similar roster the year before, they shot substantially worse, and they were dead last in the league the year before that.
Their deep forward group probably is a legitimately above-average shooting team, but it's not reasonable to expect 9.4% shooting at 5-on-5 again next year. If they land somewhere around 8.5%, that would be about 20 goals fewer.
As for the power play, there we have an interesting story. Each of the last two years they've been a middling team at generating shots (19th last year, 11th the year before), which is the best predictor of future power play success. And each year, they've indeed had middling power play results, so I see no reason to predict otherwise this year.
This section wouldn't be complete without at least mentioning their comically bad power play results in the playoffs the last two years. After posting a middling shot rate and shooting percentage during the regular season, each year they fell to the bottom four in both shot rate and shooting percentage in the playoffs. It's not something I'd fret about -- we're talking about a total of 180 minutes of play over two years, after all -- but that's not an easy thing to tell a Bruins fan who watched their team lose in seven games while going one-for-eight on the power play in four one-goal losses.
The Bruins have a precious rare commodity in a true alpha defenseman, but their defense group is not spectacular as a whole. They finished 12th in shots against per 60 minutes of 5-on-5 play this year, and while that number can be slightly inflated by score effects, looking at situations where score effects are reduced still tells the same story.
Again, many of the readers are preparing to argue that a good defense will push shots to the outside and that shot totals don't tell the whole story. And this is true, to a small extent, but the good defense that prevents a good chance from getting a high-quality shot also prevents a mediocre chance from getting even a low-quality shot -- the net result is overall a lower number of shots from a similar distribution of locations.
The result is that team effects on save percentage are modest, and a modest assessment of a team's defense can come from their shots against rate. This, of course, accepts the adage that the best defense is a good offense -- Boston's quality forwards keeping the puck at the other end of the ice probably do as much to limit shot totals as the team does by breaking up the opponent's opportunities.
So the Bruins, despite Chara's skill, don't appear to be anything special on defense. And really, the skew of their team towards forwards seems to be deliberate choice -- only Minnesota, Toronto, and Los Angeles have more money committed to forwards for next year, but 14 teams already have more committed to defensemen and a few others will pass them as RFAs continue to sign.
Others, like the Rangers, spend less because all of their defensemen are on cost-controlled entry-level or RFA contracts, but Boston's blue line is dominated by veterans.
Which brings us to one significant change from last year: Dougie Hamilton is likely to make his NHL debut. I wouldn't expect him to have a major impact as a rookie, since defensemen are a bit unpredictable and generally take a while to develop. But they have things set up correctly from a team lifecycle management perspective: if things go the way you hope they will for a top-10 pick, he'll be taking on top-pairing minutes as Chara reaches the tail of his career.
All in all, if there's a reason to predict a significant change in their goals against, it will be the...
Remember when the funniest thing about Tim Thomas was Down Goes Brown's joke about him eating a bag of $100 bills? Well, it still probably is, because DGB is great, but Thomas' outspokenness and unconventional decisions have made for some enjoyable webfare over the last year.
But now it has come to this. He will put his time and energies into those areas and relationships that he has neglected.
Thomas led the league in save percentage two of the last four years, setting a record in the process. He is the active leader in career save percentage. He is the reason a team that was consistently middle-of-the-road in shots against finished 1st, 2nd, 2nd, and 6th in goals against the last four years. This is obviously a big loss for the Bruins.
Of course, Tuukka Rask has not exactly been terrible either. His career save percentage is actually higher than Thomas's, and he led the league in save percentage himself one year. Unfortunately, since shooting percentages are variable, even after 102 games we still don't know exactly how good he is. But it's completely reasonable to expect him to be a top-10 goalie, and maybe better than that. The dropoff from Thomas to Rask might scarcely be felt. He can even match Thomas in the internet sensation department.
However, this means the backup goalie spot transitions from Rask to Anton Khudobin, who posted .914 and .919 save percentages in the AHL the last two years. Goalies are variable enough that translations are a bit unreliable, but our best estimate is that this puts him at somewhere around .910 in the NHL. If he plays something like 25 games, the dropoff from Rask to Khudobin at backup goalie could cost the team somewhere around 10 goals. The damage to depth is bad too -- if Rask gets hurt, it could be worse than that.
What happened last year
Through 40 games, the Bruins had the most goals scored, the fewest goals allowed, and the best record in the league.
At that point they had only a modest edge in shots, but an enormous shooting percentage (10.5% at 5-on-5) and save percentage (94.5% at 5-on-5). But if there's one thing I hope I've made clear, it's that shot totals chart the path amidst fluctuating shooting percentages.
Over the remainder of the season, they shot a slightly-above-league-average 8.3% and had a downright-wretched 90.0 save percentage at 5-on-5. They picked up just 45 points over those 42 games. They drew a first round opponent who finished the season strong and lost as tight a playoff series as you can have. I can't help but wonder whether the frustrations of that finish led to Thomas' decision to put hockey behind him for a while.
With the offense's shooting percentage regression costing them about 20 goals and the loss of Thomas costing them about 10, it looks like I'm projecting them to slip by about 30 goals next year. That would leave them with a goal differential of about +31, which would put them at about 102 points.
Coincidentally enough, that's the same total they had last year, and one less than the year before. I've gone through all this trouble to conclude: the team that has basically the same roster as the last two seasons should end up with about the same point total.
I hate it when that happens.