While I agree that Colt likely will not amount to starter material, the fact that Timmy Chang didn't do anything in pro football is almost totally unrelated to Colt Brennan.
I bet that Roethlisberger broke a lot of records at Miami Ohio and that the person who held them before him was not a household name.
Your point about him only having success in the preseason is slightly more compelling. I think most would agree that preseason play does not necessarily translate to the regular season. However, it certainly does not mean that he won't be sucessful either. The fact is, when given the chance to play, he has looked decent. I'm no Colt bandwagoner, but what more could you ask of the guy up until now?