The Leafs remain one of the teams who draw the lowest number of penalties in the league, while the opposing teams seem to always draw fringe penalties on the Buds and these plays are no different. Check out this non-call with Matthews getting tripped up and the subsequent tripping call against Jason Spezza, which was very questionable if the precedent had already been set:
There will be a lot of questions around whether or not the Leafs are ready to compete in the playoffs after this one. Getting beat clean 3 times in the same season by a bottom-feeding team like the Buffalo Sabres doesn't instill confidence in the team from a fan perspective. While the officiating was certainly a factor, it's not what cost the Leafs this game.
Obviously, the Buds were down a pair of goals late before the Sabres added an empty net goal to seal the deal, but I'm not so sure the Leafs were overly concerned with this game having already clinched a playoff spot. In the end, there's really no reason for the Leafs to run themselves ragged and risk injury against a team who is already out of the running.