BOSTON — For a couple years now the Bruins have been built around their goaltending and their depth at center.

They’ve found out the hard way how important it is to have plenty of pivots, with Marc Savard, Patrice Bergeron and David Krejci having suffered various injuries and subsequent absences through the seasons.

Either through trade or their own drafting, Ottawa has failed to provide its roster with similar depth. As we’ll see tonight when the Bruins host the Senators at TD Garden, after Jason Spezza, the offensive talent level drops off on Ottawa’s depth chart. So Bruins head coach Claude Julien can pretty much just roll out Zdeno Chara and a partner every time Spezza climbs over the boards and not worry too much.

Now, we all know Spezza is a dazzling offensive talent who’s off to a solid start with four goals and eight assists in 11 games. And by most accounts, including that of Chris Yzerman of the Canadian Press, Spezza is a more complete player this season — looking to shoot as much as he tries to pass and taking care of his own end.

However, against the Bruins’ vaunted goaltending and defense last month, he was held off the score sheet in the Bruins’ shutout victory. And against many of the league’s better defenses he’s not likely to get much help from an Ottawa team that always seems to be caught between contender status and lottery-bound.

Last summer, Spezza said he was open to a trade. The Sens decided against moving him, especially once they had to pay him a signing bonus July 1. He’s rewarding the club by playing some of his best hockey, but he might never again by a 90- or even 80-point player. That’s through no fault of his own as much as it’s about the Sens’ inability in a salary-cap league to provide depth around him on the wing and behind him on the center depth chart.

As long as Ottawa is a one-line team offensively, the Sens will be easy to solve. The Bruins can’t take the Sens lightly because we all know that “on any given night …” But game planning for the Sens definitely doesn’t take as much as energy as it does for other clubs.