I believe he lacks an NFL arm. He has averaged 11.84 yards per completion. That is an average number for the NFL and low for college football. He throws short patterns and deep balls, but he doesn't throw the intermediate passes that well or the deep outs. Those are NFL type throws. I think the deep out is a pass that Romo lacks as well. If he could throw that, it would open up the rest of the field for him and the receiving corps.
I think McCoy lacks NFL size. He has said that if he doesn't work out constantly and eat a whole lot of food that he will lose body mass quickly. I believe it. He is not going to grow any more and he won't get bigger or stronger in the pros. He will be lucky to maintain his current physique.
You are right, college QBs do make poor decisions. Some learn and get better and some don't. McCoy could get better at it and probably will. I just think some of those bad decisions are big plays in college, but are big mistakes in the NFL. Can he avoid the big mistakes and still make the big plays in the NFL? I just don't see it.
I would not mind if I were wrong about McCoy especially if he came to Dallas. I just see a college QB when I watch him. I don't see the upside.