Would he be too intense for NFL players? Pete Carroll has been brilliant in college but was rather average in the NFL, if I have my information correct (before my NFL watching time...)
All i'm going to say on the matter is his shtick worked fine with 18 year old kids but he may have to alter his approach when he's dealing with a 32 year old professional athlete who makes more then he does.
That's something the coaches would have to determine in an interview though so :shrug:
Edit - I will say this though. He's widely reknowned as a tireless worker and is very much 100% focused on football. So for better or for worse, you're guranteed to get his best effort.