It's pretty flawed. Just read your last few points. You say that most of Jalen's numbers were accrued vs the same defenses Tua faced. But look at the fact that Jalen succeeded vs those defenses did not lead him to succeed vs the tougher defenses. So, should we not expect the same decline from Tua? If not why not? It would be more accurate to compare Tua's numbers if you somehow calculated expected drop off vs better teams and then accounted for that. Or took Jalen's stats in the games Tua played in only but even that would be pretty flawed.
I get your point about him not necessarily being turnover prone we definitely don't know either way if he is. But you can do that without comparing his td ratio to Jalen's. That is where I think your flaw is.
I went back and just compared games that Jalen and Tua played in.
Jalen: 79-118 for 10 TDS and 1 INT - 1 TD every 11.8 attempts.
Tua: 35-53 for 7 TDS and 1 INT - 1 TD every 7.5 attempts
I realize this is not a straight up comparison because Jalen played when the score was 0-0 and Tua always entered after there was a significant lead. That said, I doubt Jalen felt a ton more pressure than Tua in these games.
About all the above numbers show is that Tua's TD per attempt ratio is better in the same games.
There is no way to tell if Tua would play better, worse or the same as Jalen against the better defenses.
To say he'd probably play worse just because Jalen does is nothing more than a guess, but the one thing that is consistently overlooked is that Tua's fundamentals are much better than Jalen's so I don't think it is a given he couldn't succeed.
In the 5 games against FSU, TAMU, LSU, MSU and Auburn (games Tua didn't play): Jalen was 56-104 with 5 TDS. In those games he threw 1 TD every 20.8 attempts. Basically, his TD to attempt ratio was cut in half in the these 5 games compared to the easier games. He threw 0 INTs to his credit, but his TD success per attempt was significantly worse.
I guess the question is would Tua's production drop by the same amount as Jalen's if he would have played against those 5 teams? Would his be cut in half to 1 TD every 15 attempts?
I guess I'd revert back to the eye test at this point and say, I think Tua's production wouldn't fall off as much as Jalen's simply because I believe his skill set and fundamentals would actually allow him to succeed where Jalen struggled against the better defenses.