The Bruins are finding out what the rest of their divisional opponents had already learned on their road trips through California: It’s a nearly impossible place to win hockey games this season.

It would have been a more interesting three-game stretch for the Black and Gold if they hadn’t lost one of their defensive pillars, Dennis Seidenberg, for the season just games before they departed for the West Coast. But they did, and they’ve been a far worse team since then.

They’ve now lost four of the six games since losing Seidenberg, have given up 21 goals in those six games (a 3.5-goals-allowed-per-game average that’s nearly double their previous number, which was best in the league all season), and have allowed eight power-play goals over that time. It’s been even worse against the cream of the Pacific Division crop: They’ve been outscored 9-4 in the two games against the Ducks and Kings, and have found themselves down by a 3-0 score in each game.

The effort and offense has been there in flashes, but the Bruins are making far too many defensive mistakes, both systems-wise and effort-wise. When they do commit a defensive gaffe, the California teams have been good enough to make sure the puck winds up in the back of the Boston net.

Claude Julien told reporters after the game it’s something that will need to be addressed and remedied prior to Saturday’s road-trip finale against a heavy, skilled, dominant San Jose Sharks club.

“It took us almost a period-and-a-half to get going here,” Julien said after Thursday night's 4-2 loss to the Kings. “We spotted them a 3-0 lead. Puck management, missed assignments . . . those kinds of things are going to end up costing you. We’re getting exposed in those areas right now [and] we’re going to [have to] get better.

“We definitely could use more from our team, from the goaltender on out. We need big saves; we need our guys to manage the puck better. The mistakes that we’re making are very costly. Everybody needs to be a little better. We didn’t get much from our top two lines tonight, and you need that if you’re going to win some hockey games. They were pretty quiet.”