BRIGHTON, Mass – Almost a week into the regular season, the Bruins are still scrambling to figure out what’s going to work for them in the middle of their third line.

Youngsters Jack Studnicka. Trent Frederic and Jakob Forsbacka Karlsson showed in training camp that they weren’t quite ready for prime time right now, but could very well be in the near future. Sean Kuraly won the third line center job of out of training camp seemingly by default after being injured for most of the preseason, and had just a single shot on goal in each of the first two games without much in the way of offense from the third line.

The Bruins freely admitted heading into the season that they weren’t quite sure what they’d get out of Kuraly offensively in a higher spot in the lineup, but the only way of knowing was to play it out during the regular season.

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“I don’t know,” said Cassidy. “That’s part of the experiment. He’ll give you effort and he’ll possess pucks. Being on the third line won’t affect his defensive game. [Riley Nash], we weren’t sure on either. There’s a little bit of growing pains there and we understand that. What we need to make sure is that our two two lines are up to speed and our power play is producing. Then the bottom two lines give us good puck possession and hard-to-play-against minutes and then let their offensive game grow.”

At the end of the day, it might just be that Kuraly is a solid fourth line center and that’s going to be his station in life at the NHL level. That’s certainly still a pretty good place to be if you’re Kuraly.

So now Bruins coach Bruce Cassidy is tinkering with 34-year-old David Backes in the middle between Danton Heinen and Anders Bjork on his wings. It could be an interesting mix with the big, strong and veteran Backes in the middle calling the shots and setting the tone for the line, and Heinen and Bjork freed to use their speed and skill while being protected a bit by their big center in the middle.

Backes, for one, was all for it when asked about it after Sunday’s practice, and has made no secret that he looks forward to the days when gets to play the center position he was at for so long during his tenure with the St. Louis Blues.

“Playing center, for me maybe there will be a little more in the legs with the crowd making a ruckus,” said Backes, referencing his anticipation for the TD Garden crowd in Monday’s home opener. “I’d say it was more of a one-way street with me communicating with them and letting them know how much it means to me when they’re talking to me as well. It’s maybe a little more imperative with a winger that’s facing the wall or getting rimmed puck, that he really can’t see anything behind him and really needs that communication rather than a guy in the middle of the ice.

“I think [my role is] exiting our D-zone as quickly as possible and being able to separate guys from pucks and get it into [the winger’s] hands, joining the rush and then being a responsible F3 so those guys can get creative down low. I don’t want to be just a passive third line checking line, I want to be an offensive threat. I think that’s a good way to play a third line role is to keep the other team on their heels. We need to get to that. I don’t if I have the Bergeron chemistry from the slot like he and Marchand do, but we can certainly get pucks to the net, find a few rebounds and get a few home. I want to celebrate a few goals with my linemates.”

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Cassidy said on Sunday that the Bruins are toggling through their options on the third line at this early point in the season, and clearly are still looking for the right combination to provide support behind the top two lines.

“We took a look at [Backes at center] today because it’s something we’ve discussed,” said Cassidy. “It’s a plan C type of thing. Going into the year we were going to look at the three younger guys and then take a look at Sean. I think the fact that Sean missed some time [in camp] means we may have to wait on that.

“We kind of toggle him and Backes back and forth. We talked to [Backes] about it and he’s got some speed and skill on the wing. That was part of the thinking. So we’ll probably look at it tomorrow [vs. Ottawa] and it’s an easy switch back if we have to do it and go back to the lines the other night.”

It doesn’t feel like Kuraly or Backes are going to be the final answer in the middle of the third line this season, however. This humble hockey writer’s hunch is that either Frederic or JFK will end up filling that spot a couple of months down the line after a little more seasoning at the AHL level. Frederic, in particular, had an impressive camp after only playing a handful of games for the P-Bruins last season, and could be the kind of player that would plug in nicely with the big-bodied Backes and a young skilled left winger.

But for now the Bruins are trying out different pieces and looking for a little stability while working toward a more permanent solution on a third line that’s very clearly still in flux after the free agency departure of Riley Nash.