And my point is Bama was undefeated through 11 games with Hurts last year, and he's better this year. And arguably, most of the same teams we've faced are worse.
Bama is definitely better with Tua, but I have little doubt Bama would still be undefeated vs this year's schedule with Hurts as the starter. I'm not talking about the what-ifs of injuries, etc - those things happen - I'm simply saying that Murray is a more important factor in OU being 10-1 than Tua is in Bama being 11-0.
To go deeper into my thought process - without Tua your entire team would look different this year. Assuming he was just lost for the season to injury, your entire team plays harder with Tua at QB, so your effort level would have diminished without him. Every single player believes in Tua. Every single player knows that Alabama loses to GA last year without him. And if he was lost before the season started, how much of this season's greatness ever materializes? IMO, none of it. IMO, Alabama could as easily be a 3 loss team as an undefeated team without Tua this year.
You cannot discount how the players felt last year. Those feelings would have instantly been realized again when Tua was lost to the team. Receivers would not be happy and your offense would be run oriented rather than pass oriented. Your defense would have been under enormous pressure from day 1, and that would have been a problem given the turnover and lack of experience.
Would you still be undefeated? Maybe, but I would not bet on it. In fact, I would bet heavily against it.
ETA - now if you are saying that the Sooners might have lost even more games without Murray that Alabama without Tua, that is fair. But Tua makes Alabama into a championship team this year. Alabama is not a championship team without him. You cannot make a bigger difference than that, IMO.