As an Alabama Homer, I'm all in on the kid. Other players are available in the draft from there, and any would have a reasonable chance of fitting in, as Saban runs basically a light version of New England's system.
I also am an Alabama fan (I live in Birmingham), and Tua does seem to have that certain "something". I can't find the quote on the internet, but on one of the games earlier in the year there was a long-time announcer that said in all of his years of watching and announcing college football there was only one college quarterback that had the same remarkable inate ability as Tua to know exactly where everyone was on the field: Drew Brees at Purdue. That is high praise indeed.
Plus, there is a writer on "The Ringer" (Bill Simmons website) that seems to think that Tua is going to be the next truly great quarterback:
Tua Tagovailoa Is the Quarterback of Both the Future and Present. He also correctly points out in the same article (with an old reference link as proof) that he was one of the very few that predicted that Patrick Mahomes was going to become what he has become.
That said, it just seems like tanking is completely anathama to BB, I just can't imagine him ever doing that. I've heard many interviews where he seems to be prouder of his record of sustained excellence than anything else. It's also difficult for me to believe that the Pats will be near enough to the top of the draft to trade the farm for him.
However, just like Brees is, Tua is a bit of a non-traditional talent, and I'm not sure if he would fit on every team, I think it will take a pretty unique offensive mind to use him correctly (similar to how Sean Payton uses Brees). Perhaps the best bet that the Pats getting him is if he gets picked to death in his junior year as too short, injury prone, etc., and he falls a bit in the draft. Heck, he seems to suddenly fall in everyone's eyes just due to one bad game when he injured his ankle against Georgia, so who knows what his eventual draft position will be.