Prove me sitting is better than starting right away without using "I'm hoping for something similar from Tua". Andy Reid was already winning before Mahomes, Packers already had a HOF QB when they drafted Rodgers.
Here's a question for you... Would Mahomes be considered a bust right now if KC had started him day 1 in your opinion? In other words, do you think sitting on the bench for half a season is the reason he's so good right now?
So two things here: I don't know that it is provable that someone is better for sitting or playing ... because we cannot prove a negative, and one of those two things did not happen in each instance. Best I can do is suggest that there are similarities and benefits to each approach. As for Mahomes, he had elite traits of arm strength and off-script production, with raw or poor traits in things like size, mastering the system and decision making. What Andy Reid did was provide reps for Mahomes to learn and gain experience without crushing his confidence, via practice reps, virutal reps, coaching cut ups, film analysis, etc. For Mahomes, he was able to learn how to avoid poor decision making through these tools. For him, it took longer than it probably would have taken had Josh Rosen landed in KC, but Rosen would have needed to learn how to improvise the off-script stuff, and that is hard to do. Since Josh Rosen didn't have a QB guru like Andy Reid tutoring him, and honestly Rosen had an attitude issue preventing learning from anyone for at least the first 1.5 years in the league, the learning curve would be different.
Tua missed time in pre-season because of Covid-19, and lost chances to fully generate muscle memory nursing a rehabbing hip. Tua's strength is decision making, and his weaknesses are his arm and size. What Tua needs is experience going against the speed and athleticism of NFL DB's who understand your complex offense better than you do, and are all super-twitchy to get to and disrupt or intercept slow developing plays or QB's who are thinking rather than reacting. Tua needs to master the playbook. IMHO, best I can tell you is that doing just going through the motions on half-speed reps while he cannot put full torque into his throws simply is not going to give him the practice reps he needs to judge that timing properly.
As to your second question, I can't say how Mahomes would have done, because we can't go back and try it. But, my guess is that he would not have been a bust ... but he also would not have played his 2nd year at an elite level, because he would be pushing through his mistakes and struggling with confidence rather than playing instinctively. No evidence to back that up ... because the question itself is pure speculation, so all I can really do is speculate. But that would be my guess. What we do know is that during his draft most NFL evaluators thought he needed major development but had an incredibly high ceiling. Most people thought he was in an ideal situation at KC with Andy Reid to help him grow and build a system around him to take advantage of what Mahomes was comfortable doing. They surmised that he would not be thrown to the wolves on day 1 because KC had a QB, and that it would benefit Mahomes to sit and learn. Well, whatever the reason, Mahomes did sit and did learn and did develop incredibly quickly and was highly successful in year 2. Can't really say what would have happened if he had played right away ... but the outcome seems to support the initial scouting reports of Mahomes and the projections of most NFL evaluators. Hope that addresses your questions ... all we can really do is speculate vs. a situation that did not happen.
I feel like if Tua had been fully healthy and this had been a normal pre-season year, and our offense was loaded like the Cowboys with a great OL, great RB, and solid WR corps., that Tua could have a Dak Prescott type rookie year and start right away. But he didn't enter this year healthy, we do have Covid-19 sucking out his chance for a proper offseason, our OL is patchwork and our RB is a stable of new guys and our defense cannot stop anyone putting even more pressure on the offense to score every drive. None of those factors help Tua become instantly productive.
