Perhaps a question of semantics. If he didn't move from #3 to the top of the pack in the off season,then spring and fall camps then our staff doesn't see his skills the same as some observers at this site.
Per the comments of the coaches he moved up from a clear #3 well behind the others to just barely behind them. Isphording said something along the lines that he'd never seen any QB improve as much in one year as Windham has improved in the last year. If he improves again over the next year, where will he be?
From what little I've seen, Windham has the best arm of the three QBs. That doesn't mean he's the best overall QB. There are a lot of other things, such as game management, audibling, running, sensing pressure, knowing when to throw the ball away, being a leader, etc. Some of those I think Vick is the best at, and others I think Sprague is. As to who is the best overall QB, that's the call the coaches have to make.
I do agree with C. Money, though. Windham had a year off from football, and that set him back quite a lot.