As an Ohio State fan, I can tell you that Troy Smith is a gamer. Whatever happens on the practice field is fine and dandy but when it comes down to it there are always certain players that you know you can count on when game day rolls around, and Smith is one of them. If you followed his college career at all you would know that he got beaten out for the starting quarterback role at Ohio State by Justin Zwick, a pro-style quarterback who was rarely fantastic but usually solid. When Zwick got injured Troy was given his chance and what he did on the field was what kept his name at the first spot on the depth chart, not necessarily what he did in practice.
I would also add that I'm trying to make it look like Smith cannot practice well, merely that he's not really a 'practice hero' (at least this is how I have interpreted it), which could hurt him in the NFL, moreso than it did in college.