Lots of good discussion here. I will add a few thoughts.
While I think we can improve some in the way of pass protection in our current scheme, I think we are unlikely to make a huge jump. Keep in mind, our guys line up with wider splits than pretty much any other OL in the nation. When you combine that with them having a hand on the ground as well, it makes it nearly impossible to protect at the level many of us are looking for. We do those things because they are good for the run game and they give us a good "run look" when we are really going to pass. That scheme is unlikely to change. It will hardly be a kiss of death in the passing game however. In my mind, there are two areas that need to improve for the passing game to take off, even with those protection issues. First, we must handle the attacking defense better in the run game. Defenses were blitzing us almost every play with total disregard for run or pass. They figured it was good against the run and if it ended up being a pass play they would just keep on coming. If we execute the run phase better against a flooded LOS, then it will help take care of that problem. They will do it less if they get burned. Secondly, we must learn to dump off to check down receivers more consistently. Those plays are very often there and we haven't hit them because we were forcing the ball down field. The screen against the blitz is one of the most tried and true strategies in football. Those plays often end up in huge gains.
As far as QBs are concerned, we have had a string of guys with considerable limitations in the CPJ era. None of them, including the guys in camp now, will ever be considered lights out throwers. Nesbitt had the arm strength but severe accuracy and touch issues. He excelled throwing the 50+jump ball, but ask him to throw a 15 touch pass leading a receiver and he was hopeless. Tevin developed as a QB who saw the field and went to the right guy, but he couldn't throw accurately on the run and he didn't have the raw arm strength to hit the deep receiver running past the defense. Vad had the ability to throw well when he stepped into the release, but he didn't consistently do it. He didn't see the field real well either, threw to the wrong guy a lot, and forced the ball deep into low percentage attempts when automatic 10 yard runs and dump offs were right in front of him. What encourages me is that we have a couple guys in the two deep that, despite some limitations, have the ability to improve in these areas.
I have seen JT keep his eyes down field while scrambling and finding guys in creases. He actually throws quite well on the run, well, going towards his throwing side anyway. He has the arm strength to get the ball down field. We haven't seen him do it in a college game, but I saw him flick a ball 45-50 yards down field while on the run several plays on his HS film. The field isn't longer in college. Arm strength doesn't decrease without injury. He can lead receivers and throw with a certain level of accuracy. He doesn't need to be all world as a thrower. He just needs a decent combination of the things mentioned above to be successful. I think the mass opinion is that he will be good for the run game. If that turns out to be true, I think we will be surprised how well the air attack works. He needs to stop forcing everything and telegraphing his throws on well run designed routes. When scrambling and improvising that weakness gets mitigated somewhat, but when standing in the pocket he needs to control the defense with his eyes better and release the ball into safe areas on time.
TB sees the field. I hope by now that is beyond dispute. I happen to have a lot of respect for him as a decision maker. I don't have as good a feel for him as a thrower because of the spring game weather and the garbage time running he did in games last year. We will have to see. On the surface, he appears to have, at least, TW's arm strength. Hopefully it is better, but I can't say for sure. I think he recognizes where to throw ball...you know... to holes in the defense.
In summary, I think both of these guys have a chance to be a bit of a remedy for the alarming weaknesses of their predecessors, even without being prolific. I think most of us would have considered NIck Marshall an effective thrower last season. What does he have that the guys on our roster don't?