I mentioned it in another thread, but I agree that Tua is better, and the road where Lawrence makes up that ground is long and uncertain. The ability to process quickly and accurately is the most essential trait to a QB's floor and ceiling, and this is the very area where Tua is elite and Lawrence is merely good for his age. Most QB's never get to Tua's level. Studying and putting in the work is essential, but it will only take you so far. Again, speed is just as important as accuracy, because if you're right late, you're wrong, and much of the speed element is something you have or don't. I don't think anyone questioned Tannehill's intelligence or work ethic. He just processed info too slow. Lawrence, today, processes info too slow to be a great QB - or even a good QB.
I expect that to improve, but I don't think you can project him to bridge the gap with Tua. Thankfully, we don't have to. We get to watch him for a couple years and see how much he improves.
To me, it's not a foregone conclusion that Lawrence is QB1 in 2021. Justin Fields has the talent to overtake him. I'd still say Lawrence is the favorite to be QB1, but if Lawrence doesn't improve the way we hope he will, Fields is the more appealing physical talent, and Fields could be the one that shows he can process info quickly.
The overarching point is that Tua is where these guys are trying to get.