All of Toronto's offense came from players with fewer than five goals this season. The goal scorers have combined for just 13 goals.
Luke Schenn, Mike Brown and Keith Aulie also scored for the Maple Leafs (32-31-10).
Adam McQuaid and Dan Paille had goals for Northeast Division-leading Boston, 1-3-3 in its past seven games.
Toronto kept pace with eighth-place Buffalo, which beat Atlanta 8-2 on Saturday. The Leafs are four points back with nine games remaining.
It was the first trip back to Toronto for Tomas Kaberle since the defenseman was dealt to Boston on Feb. 18. He played the first 878 games of his NHL career with the Maple Leafs — leaving him eighth on the franchise list — and admitted before the game that he had "mixed feelings" about his return.
A video tribute during the first period earned Kaberle a standing ovation, and he acknowledged the fans with a couple waves. Otherwise, it was a night for him to forget.
Schenn opened the scoring at 9:44 of the first period. With Bobby Orr watching from a private box, the stay-at-home defenseman went end to end and beat Tim Thomas with a high wrist shot for his fourth goal.
McQuaid tied it 1-1 just over two minutes later when his shot from the corner deflected off Dion Phaneuf's skate and past James Reimer. The Maple Leafs goalie was solid after being given the night off Thursday when Toronto lost 4-0 at Florida.
The first goal of Kadri's career came at 12:26 and needed video review. His wrist shot from the point hit McQuaid's arm and fooled Thomas. The 2009 first-round pick flashed a big grin when his name was announced.
Toronto blew the game open in the second period shortly after Reimer denied Tyler Seguin on a clear breakaway. Crabb and Brown scored 39 seconds apart to make it 4-1 for the Maple Leafs and chase Thomas from the net.
Tuukka Rask was sent in as a replacement, but he allowed a wrist shot from Aulie to beat him at 17:23. He watched the third period from the bench after Thomas came back in.
Paille scored with less than 20 seconds to play.
Notes
Toronto matched last season's total of 74 points. … The Bruins are 7-3-3 since acquiring Kaberle. … Kadri has played in 21 NHL games. … Maple Leafs tough guy Colton Orr skated on Saturday morning. He hasn't played since sustaining a concussion in a fight on Jan. 20.