I think part of it is how efficient power plays are. The margin between winning and losing is paper-thin, and that one dumb penalty can be the difference. It was in Game Five between Vegas and Dallas.
The Leafs were "sending messages" from the opening face-off, dressed Reaves, etc. and promptly dug themselves into a 3-1 hole. Their sputtering power play didn't help, but Boston clicking on theirs was a huge factor.
Florida did a solid job keeping Tampa's lethal PP off the ice, and cruised to victory in five games.
I haven't loved some of the low-event hockey, like Game Six between Vancouver and Nashville. But teams are definitely going to great lengths to stay out of the box.