See some complaints about referees here, and I disagree.
Looking at replay, it looks like McDavid is running a pick on Garland. Not 100% sure who pulls the other player down once there is contact. It actually could've been McDavid, he seems to be leaning in. I figure wasn't easy for the refs to decide who to call there, so hard to complain. Once on the ground, Garland is holding McDavid, but this "wrassling" happens all the time when the two players are tangled on the ice, and I never see this kind of thing getting a call. And McDavid getting a 5 minute major after the crosscheck is also pretty normal.