"They pretty much just slapped us," he said postgame, according to The Athletic's James Mirtle.
The Leafs were embarrassed in their own barn, losing by a final score of 6-2. Tampa Bay held a 5-1 lead when the second period concluded.
"In the third period, we pretty much just quit," Matthews told TSN's Kristen Shilton. "That's on us as players. We have to wake up and do a much better job and hold each other accountable."
Teammate Nazem Kadri offered a different response when asked if the team quit in the final frame.
"I don't think so. We're not quitters," Kadri said, according to TSN's Mark Masters. "We've never been like that. We always finish it to the end. Did we want a better (overall) effort? Of course."
The Bolts controlled 55.8 percent of the shot attempts and 57.1 percent of the high-danger scoring chances at five-on-five during the contest, according to Natural Stat Trick.
If the Eastern Conference standings remain unchanged, Toronto and Tampa Bay would meet in the second round of the playoffs should each team win its first-round matchup.
With the win, the Lightning became the seventh team ever to reach 110 points in 70 or fewer games.