That's a very solid point.
Ppl say things like Tua needs to check down, run on occasion, he missed wide open receivers, etc. All of which is true to one or another extent. Many even blame McD, which may also have situational validity.
It was year one in a complex system where, to be at top effectiveness, the receivers and QB have to read defenses, leverages, etc exactly the same. Some call it "being on the same page". Previous seasons he first had an offense that was designed for an entirely different QB's skill set. Then, he had a clown show of offensive incompetence, and. HC who's philosophy was play not to lose, rather than win on that side of the ball.
Tua's durability questions aside, and given the large amount of progress he made last year, it's more than reasonable to expect another leap this year. I also believe a guy like McD will be introspective, and self correct some of the things that went south last year.