You ask some really good questions. I like it.
Tua doesn't necessarily lose stock in my eyes because of the recent injury, but it does concern me. He doesn't lose stock because this is the first game he'll ever miss. I give him credit for toughing it out last year and playing injured down the stretch against all the best defenses college football could throw at him. There are no defenses in college football this year that can stack up to Clemson's or Mississippi St.'s defenses last year. Tua had to face both.
Secondly, he doesn't lose stock because the procedure essentially all but prevents him from being able to sprain the ankle in the same way again.
He's proven what he can do when he's not hobbled.
There's two things I want people to think about that the common fan just doesn't observe. One, Tua doesn't fumble. Pay attention to how easily he handles and adjusts to poor snaps, handling the football, getting hit, etc.....doesn't matter. He always has complete and absolute control of the football. 100% of the time. That is not normal.
Secondly, he never gets a pass batted down. I've seen all these 6'6", 6'5", 6'4", quarterbacks get passes batted down every game. Not Tua. And he's done this with guys in his face all the time.
He's thrown 626 passes at Alabama and I can't find a single time I've seen it get batted down. Not a single time. Not even once. It's because his instincts and pocket manipulation are so rare. It's what made Drew Brees special.