QBs that play their whole college (and probably HS) careers standing in shotgun are not going to be prepared to line up under center and make reads and drop back and pass at a higher level where everyone is faster/stronger/more agressive.

He's right that it doesn't mean a guy can't learn it. I guess that's what he is trying to say, but I think the people that say that are right, you don't know from their body of work in college IF they can play under center effectively.

There is a TON of evidence that not every QB can learn it and be good enough to be successful n the NFL just because he lit up scoreboards from the shotgun formation in college.