Truth is the Ovechkin hit on Campbell, or some form of it, happens in almost every game, but if there's no injury, there's no penalty.
Craig Adams dirty hit on Alex Ovechkin:
Compare how Alex went into the boards head first with Brian Campbell who went into the boards with his right shoulder. With shoulder, not with his head first like Alex Ovechkin. It tells you it was not a hit from behind, it was a sideways hit.
Campbell knew Ovie was behind him, in fact took a second look just before the hit. He in no way prepared himself to be hit (or even shoved?), which seems to be commonplace these days in the NHL. There was a time in hockey when D-men would 'lunge' towards incoming hits with their shoulder, mitigating much of the impact.
Campbell just assumed Ovie wouldn't hit him and fell into the boards like a piece of spaghetti.
Are we really going to remove all responsibility from players who have the puck in terms of awareness? Can you hit anyone anymore?
Reader's comment from The Spin