Bergeron/By S. Bradley

There are plenty of flaws with the way the Bruins’ roster is formulated.

In the post-expansion, salary-cap-restricted NHL, every club has its weaknesses.

But one thing that has obviously gone according to plan for Boston this season — despite the assorted struggles of Marc Savard, since his return from post-concussion syndrome, and David Krejci — is that they’ve been covered at center regardless of injury or illness.

It’s a plan the Ottawa Senators might’ve been smarter to follow coming into this season. The Sens land at TD Garden for tonight’s game muddling through a five-game win-less streatk (0-3-2), with all those games occurring after an injury knocked star center Jason Spezza out of the lineup. In fact, the Sens, 27th in the overall NHL standings heading into tonight’s action, are 3-5-2 this season without Spezza. Even with Spezza in the lineup for all but those 10 games, Ottawa has struggled to muster much offense and ranks 29th in goals per game (2.21).

The Bruins (13th in goals per game at 2.83), on the other hand, were able to weather lengthy absences by both Savard and Krejci. Without Savard in the lineup, Boston was 13-8-2 this season. Without Krejci, who was out with his own concussion while Savard was still on the sidelines, Boston compiled a 4-3-0 record. Basically, the Bruins’ depth up front — particularly at center — helped them stem the tide.

When you’re able to plug in veterans Patrice Bergeron and Gregory Campbell, and No. 2 overall pick Tyler Seguin as your top three centers due to injury to others, you can keep your club afloat for at least a ittle while. And that depth can also help when a player or two is in a slump. Krejci has recorded just one point in his last seven games. Savard is now point-less in three straight. But Bergeron, and last night in Pittsburgh Campbell, can step up and provide just enough punch for the Bruins to earn wins and points and sit atop the Northeast Division.

As the Bruins saw last night in Pittsburgh, where Sidney Crosby was sitting out with a concussion, teams can go through some difficult times without their star center. And this season, it has seemed like top-line centers have dropped like flies, as documented by the Daily Faceoff last week.

That’s why the Bruins had no qualms about drafting Seguin despite their depth at center, and had no problems investing long-term in Savard last winter and Bergeron this fall.

The Bruins have built their team up the middle, so to speak, from the goaltender out to the centers. So in as much as they’ve been able to get by when a pivot or two has had to sit out, the Bruins’ philosophy has worked. Tonight they’ll try to keep it going against a club that hasn’t managed to make due without its No. 1 center Spezza.