It can be considered overrated, but it's not something that you can just ignore and slide under the rug. Physicality is the name of the game, he's not going to be playing boys in the NHL.
I agree as long as we're talking about cycling the puck, controlling the puck along the boards, driving to the net and that sort of thing. That said, you lose me when you start talking about "finishing" your checks. That Mantha won't do and I don't really care either. It's fine for defensive players but I wouldn't want a potential high-scoring guy wasting his time trying to start hitting and fighting.