Kuraly tied the game at 1-1 at 12:11, one-timing Pastrnak's pass over Howard's blocker for his fourth goal.
"That's exactly the kind of hockey we preach," Cassidy said. "He got back to the blue line to fill in for a defenseman, he kept the puck alive and he got rewarded with a goal. That's a Bergeron special, and our young guys are learning from him."
Krejci gave the Bruins a 2-1 lead at 14:17, slapping home a rebound for his 10th goal.
Heinen scored his 12th of the season at 8:21 of the third period, snapping Kuraly's pass past Howard from the slot for a 3-1 lead.
"We just kept scrambling for the puck and when Sean got it, he gave it to me in a perfect place to shoot," Heinen said.
Nielsen scored with 1:24 to play to make it 3-2 with the Red Wings having an extra skater after pulling Howard, but Nielsen missed a rebound with a chance to tie the game in the final minute.
"I saw the puck but it was bouncing and I just fanned on it," Nielsen said.