From all accounts it sounds like he is athletic enough.Not to sound pessimistic because we have yet to see Howard play but I really do think he could benefit from an entire season/off-season in an NFL program.
When Rankin came in, I also mentioned that he was carrying a lot of bad weight. It sounds like he has come into OTA's with a bigger upper body and a slimmer waist. I think Howard will need the same thing before we see the 1st round investment. (Probably why he is getting initial work at guard)
He is going to have to make his fair share of rookie mistakes so why not start him asap? The sooner the better.
Cant keep him wrapped in cotton wool for ever.