The difference between a real franchise defenseman like Chara, Pronger, etc. and a good defenseman like McAvoy is night and day.
Charlie is an excellent defenseman, even the number one the Bruins projected him to be.
More than a stay at home, shut down D who can be physical (though not consistently enough to strike automatic fear into opponents), at his best he does many things well.
Again, I don't see him as a natural power play quarterback. He's a pass first guy, which is fine, but that trait is predictable, possible to neutralize, and therefore of limited value.
None of this means McAvoy isn't a top D in the NHL.
What it means, at least to me, is that his floor is solid and well established, but perhaps his ceiling is as well.
I'm not certain that's worth 9 million a year.