I would definitely feel better if we were able to draft a Tua Tagovailoa that was more in line with conventional metrics. Most assuredly we all would. It would help end a lot of debates which themselves are really the topic here.
The fact that most successful QBs are "prototypical" in size hides the reality that most failures are as well. Tannehill was the prototype. So were Sam Darnold, Carson Wentz and 1,000 others. Their collective failure led directly to the Dolphins passing on a similar QB in Justin Herbert who's been equally disappointing in not turning around the fate of his team, the Chargers.
The preference for someone with real pocket instincts, an ability to execute an ever-evolving offense and an instinct to attack despite his smaller stature was precisely what the Dolphins demonstrated coming off the promise of "prototypical measurables" that so often fall short and most certainly did with Tannehill.
A lesser number of small guys have been great, too, obviously, but that's also partly because small guys are less often major QB prospects to begin with. We can look at Steve Young, Drew Brees and Russell Wilson. Their being "exceptions" is only true if a large number of small QBs are being drafted which of course isn't the case. Small QBs are simply altogether rare. The position doesn't select for it. But the question isn't whether small QBs are rare but rather if the small one we have is good.
Those smaller guys all have to bring something. Young and Wilson were dynamic escape artists. Brees was really efficient and at the end began to achieve a combination of cmp%, int% and sck% that made his offense really hard to stop. Tua has to do that as well, but you can't expect perfect at year #4.
What you should be doing is looking at the projections and you're not even giving that the time of day. I'd obviously trade Tua for Pat Mahomes, Lamar Jackson or Josh Allen but that's not in the cards. You could've said the same about trading a young Drew Brees for prime-of-his-career Aaron Rodgers. There's always a best-in-class.
But the fact is that you have Tua here today. You'll never have Mahomes, Allen or Jackson. You have to make peace with that. If you're for ditching Tua--fine--but you haven't made a good case for whatever you imagine the alternative being. And that's likely because your attitude is based more in fantasy than in reality.
I don't mean any offense by any of that mind you. Everybody wishes they had Pat Mahomes.