Minten tied it 1-1 at 12:48 of the second period when he was able to knock in a loose puck at the right side of the net that Marat Khusnutdinov slid to him while Hofer was trying to cover the puck.
Kastelic tipped Victor Soderstrom’s left point shot after Kuraly got a piece of it to make it 2-1 at 14:34.
The Bruins outshot the Blues 13-3 in the second.
“I don’t feel like it was our best first,” Minten said. “We brought more urgency to start the second. We started to pour it in there in the second. Three games in four nights for them, that’s how you’re going to score is to get some greasy ones. That was our plan to go to the paint.”
Thomas tied it 2-2 at 4:51 of the third period when Buchnevich picked off Bruins defenseman Andrew Peeke behind the goal and fed a pass to Thomas, who finished from in tight.
It was the momentum boost the Blues were looking for that never materialized.
“Just a little bit too loose,” Thomas said. “We allowed them too much time and space in the D-zone, and they made us pay.”
Kastelic restored Boston's lead to 3-2 with his second goal at 8:01. Nikita Zadorov sent a shot from the left boards that hit off Kuraly and dropped into the crease, where Kastelic tapped it past Hofer.
“I’m just naturally a bigger guy, so I try and take pride in getting (to the front of the net) and just trying to get in front of the goalie and get dirty ones like the one you saw tonight,” Kastelic said. “I’m just trying to always improve in that area. Our whole line has the ability to get to the net. It’s fun to play that way.”