We wouldn't have been any worse off with an untried QB, unless getting beat worse counts.
One reason I've been rather entrenched on the issue, is because I don't see a choice being good or bad based on the outcome, but rather based on the principles behind the choice. With the Hurts scenario at Alabama, it is easy to judge things after the fact, since we know the outcome (and I will repeat my assertion that Tua should be and will be the starter). But, that doesn't make the choices made previously bad ones, nor does it mean similar choices in the future would be bad ones either.
I was looking over some stats, and the worst three game stretch of any Nick Saban Alabama QB was Greg McElroy in 2009. He wasn't exactly inexperienced at that point either, he was a redshirt junior (so older than Hurts is now) playing in his 11th game when he started having issues. This wasn't the toughest part of the schedule either, but against Ole Miss, South Carolina, and Tennessee (two of those games at home) he threw for a
combined 359 yards 0 touchdowns, 2 interceptions, and a long of 22. He also ran for 11 yards on 11 attempts for 0 TDs.
This poor stretch culminated in a 120 yard performance against Tennessee where he threw for a long of 19 yards and the offense only mustered 12 points. The only reason they won the Tennessee game was due to the Cody blocks, it had nothing to do with McElroy playing well. Now, you might counter that this was different, because they didn't have Tua... but Alabama did have AJ. Make no mistake. McElroy had a dreadful stretch, as bad a period passing the ball as anyone in recent memory, and this probably should have cost Alabama not only a game against a hated rival, but a championship as well.
Now, Nick Saban could have seen the Tennessee game coming and started AJ. He could have, but that could have cost Alabama a championship. We know how great AJ would perform later on down the line, but there's no certainty he would have in that moment. Saban stuck with his QB and it turned out ok, but it was pretty darn close wasn't it? That wasn't the end of it either, McElroy was hurt for the Texas game and put up nearly no production. He threw for 58 yards on the championship game, but yet again Saban stuck with McElroy and he has his only undefeated season to show for it. Now, the truth is that might mirror Hurts' freshman season more than anything else, the only real difference being there was no knocking Watson out of the game or a pair of miraculous special teams play, but it also informs the choice that Saban made last year. Do you go with the unproven but very talented guy, or do you stick with your limited but more experienced quarterback? Here's the thing, AJ was ready to go for the championship game to, and if Saban had to he was ready to make that switch as well... The key here though, and we have to remember this, is if Saban put AJ into the Tennessee game or the Texas game, the outcome could have been worse. Alabama could have lost those games, so, in retrospect we have some good outcomes and on the other bad outcomes, but with very little difference in the decision making.
That aside, the other thing worth addressing is the notion that unproven bench QB is going to be able to perform at a high level. If we put being able to pass downfield against an elite defense as the standard, the truth is most simply won't be able to. Alabama usually doesn't have an AJ or a Tua on the bench, and even if they do it doesn't mean they're ready to go. To give an example, the recent past has included guys like Alec Morris, David Cornwell, Parker McLeod, and Cooper Bateman. In the case of Parker McLeod, he's never thrown a pass in college. Bateman is a good example though, because he is actually one of the few times Saban really did throw the unproven backup out there, and it cost Alabama a game. It wasn't just that though, Bateman's career long is 31 yards and I'm pretty sure that didn't come in the air. From what I can tell he's not just limited in the downfield passing game, he literally can't do it. So, remember when you talk unproven and untested, the odds of that guy being able to get it done against an elite defense are actually pretty slim and that can lead to a loss more easily than playing a proven quarterback.