My guess would be none. Talent scouts will find their players. Doesn't matter who is coaching them or where they play.
Look at Tom Brady. The guy was #199 overall in the 2000 draft and played behind Brian Griese at Michigan until 1998 and 1999. My point is that the talent will always come to the top, doesn't matter who happen to be coaching him or what his college career was like.
Well it certainly helps to learn something in college. Tom brady is the exception not the norm. Most players who have a good college career go on to do well in the NFL. Also doing well in college gets you paid on that first day of the draft, and Callahan has done nothing for these guys to have a buzz about anyone of them so they can land that payday. At this rate we wont have anyone who can even pull a Ryan Leaf. I would rather get my payday and have a shot at the NFL than to be coached so badly in college I dont get looked at and never have a chance.
Mike and Mike had a good segment on this last week. They went through all the starting QBs in the NFL. About 1/3 were dark horses like Brady, and about 2/3 were highly regarded 1st or 2nd round picks. So you're right in that respect, that the Bradys and Favres are the exception.
However I would have to disagree with the idea that most good college players go on to do well in the NFL. Does anyone think Troy Smith is going to go light up the NFL...Tommy Frazier, Eric Crouch, Zac Taylor for that matter (and that's only QBs)....There are tons of players out there who will excel at the college level but lack the necessary skills to be NFL starters...