The Bruins were flat.

BOSTON — Bruins head coach Claude Julien called his team’s effort against Buffalo tonight “flat.”

And there’s no doubt the Bruins played like day-old opened soda in dropping a 4-2 decision to the Sabres at TD Garden.

Thomas Vanek broke a 2-2 tie 5:13 into the third period on an end-to-end rush after a Nathan Horton giveaway for what proved to be the game-winning goal. Vanek then added an assist on Jason Pominville’s insurance goal.

Here’s a glance at the box score:

•After my post about Tuukka Rask’s quality starts this afternoon, the goaltender failed to post one against Buffalo for the second time this season. He allowed four goals and stopped just 29 shots.

•Dennis Seidenberg and Gregory Campbell scored Boston’s goals.

•Ryan Miller stopped 38 Bruins shots to earn the victory.

•Defenseman Andrew Ference returned to the Boston line-up after a three-game absence with an upper-body injury. He skated 18:22 and fired one shot on net. Adam McQuaid was scratched. Before the game, Julien said the rookie had been playing “banged up” so he could use the rest.