1: In regards to performance, upside, and player skill set; where do things stand right now?
2: Outside of injury, under what scenario(s) do you think Tua could be named the starter before the season in 2018?
3: What do you think the likelihood of those scenarios are?
4: What are the reasons why Jalen will keep his starting job?
5: What, if anything, needs to change for Jalen to keep his starting job?
I'm sure that Krazy is putting together a comprehensive answer to your post. But in the meantime, I'll offer my thoughts.
1: In regards to performance, upside, and player skill set; where do things stand right now?
If we run a spread RPO type offense, then Jalen is better suited. If we run a standard Pro-style offense, then Tua is better suited. Unfortunately, I don't think either QB will be very successful in our current hybrid RPO/Pro-style offense. We need to commit to an offensive philosophy and play the QB that is best suited for that offense. Trying to run something that's kind of this and kind of that doesn't work. OTOH, there's a reason that we're not putting Tua in when we need to air it out and the game is on the line. I think it boils down to Saban's aversion to turnovers - or even the risk of turnovers.
2: Outside of injury, under what scenario(s) do you think Tua could be named the starter before the season in 2018?
We commit to going with a Pro-style offense that balances runs (by the RBs) with passing. Will that happen? Who knows. But Tua is much more skilled as a passer.
3: What do you think the likelihood of those scenarios are?
40%, depending on what happens with the playoffs/bowl games. I think we're moving back to a Pro-style offense, which is one of the reasons Daboll was hired. But it won't happen overnight. Personally, I think Daboll could do well as OC with Tua at QB running a Pro-style offense. I don't think he quite knows what to do with Jalen.
4: What are the reasons why Jalen will keep his starting job?
Leadership, poise, composure under duress, experience. We know he has those intangibles. Does Tua as well? We don't know yet. But to keep his starting job, Jalen needs to continue to improve in the passing game or none of that matters.
5: What, if anything, needs to change for Jalen to keep his starting job?
As stated above, he needs to improve his passing skills and Daboll needs to design a game plan that fits what he's capable of doing. He needs to be consistent hitting the quick slants and mid-range passes over the middle.
I'd like to see us play both QBs and force our opponents to stop both the RPO and Pro-style attacks. It could be a real spark to the offense if it was struggling to switch tactics, even if for just a few series. Coach Bryant used to bring in his second string for the 3rd or 4th possession. And he didn't hesitate to make changes during the game if what we were doing wasn't working. That's my biggest concern with Coach Saban. He seems to be very stubborn about sticking with the game plan, even if it's not working. In that regard, Coach Bryant was a much better game day coach.