I think Tua will be an excellent starter, but the question is who's the better starter right now. It's a practical tautology that the only guy to win NFL games gives you a better chance right now to win NFL games.
There is a tendency to just assume that prospects will pan out,, and that there's no room for high floor players like Brissett. We just saw firsthand that that's not remotely the case, but the delusion persists.
And there's a big difference between not being injured and not being hurt. Lower body injuries like the one Tua suffered don't ever really seem to go all the way away. That kind of injury has killed plenty of other QB prospects, which adds to the risk a team is taking if they hand the reins to Tua before he proved he can be effective despite the pain and loss of mobility.
A rookie with no NFL experience and serious injury concerns, who is currently hurt, gives you a better chance to win right now than the guy who came in to back up Luck and went .500 in his starts.
I know there's a certain frustration with Brissett because of how the second half went but that's absolutely insane.