The real problem is the distribution. There is very little correlation between the shot blocking skill and the number of blocks. If somebody with no skill in shot blocking is blocking at 0.5 - 1.0 bpg -- those with the skill are blocking only a fraction higher -- then the skill is practical worthless.
I agree that distribution is a problem. I said this a couple of posts up.
I don't think this necessarily makes the skill worthless for centers, since shot blocking on guards doesn't help you as much when the opponent is playing an inside tactic.
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."