"They scored on pretty much every [chance] they had, that's it," Cooper said. "And you can't pin it on the goaltender."
Lightning goalie Andrei Vasilevskiy allowed five goals on 23 shots, but two were on a deflection, two were on an uncontested one-timer from Bergeron in the slot after a breakdown, and one was on a long shot from Rick Nash after the Lightning backed off too far and gave up too much room.
Jake DeBrusk also scored an empty-net goal.
"We have to raise the battle level in the defensive zone," Cooper said. "For all the battle level we had in the offensive zone, if we turn that into the defensive zone for some of those plays, maybe they don't go in. I think that was frustrating for the guys, spending the amount of time they did in the offensive zone, not being rewarded, and the Bruins were rewarded for just coming down and making a play. But that's what that line does, they make plays. Right when you think you might have them, they can burn you. That's what they did to us."
Point, Palat, Johnson, Stralman, McDonagh and Hedman should have the chance to go against Bergeron's line again in Game 2 at Amalie Arena on Monday (7 p.m. ET; NBCSN, CBC, TVAS).
Cooper didn't sound like he was interested in going away from his preferred matchup on that line because the numbers tell him it's not worth it.
"I don't even know if they had 10 scoring chances in the game," Cooper said. "If you were going to tell me that we were going to hold Boston to [almost] as many shot attempts as we had shots on goal, I would have taken our chances.
"Everybody breaks down at some point in some situation. Sometimes it may hit a post. Somebody might miss the net. Somebody might get a huge shot block. Somebody might get a huge save. At those times we broke down, none of those things happened for us. It's the game."