I have to agree that tackle is the way to go, if you absolutely can't trade down.
The problem I have with WR at that pick is that, historically (and I have looked into it in depth), it hasn't proven to have "value" because of the erratic return potential. In other words, it is far more likely you get average, as opposed to "elite". That's not, necessarily, reflective of any specific player available this year, it's just historical fact. In this particular case, even the measurables aren't suggestive of breaking any trends. I've seen some suggest that a receiver has a higher impact than a tackle, but that is a flawed arguement, IMO, because if "average" is the suspected likely outcome, you can get that later in the draft. Even if you have to take two to get one, it is still better value, as far as risk/reward. If a Calvin Johnson type guy were in the discussion I may feel differently, but that is certainly not the case. None of the high rated guys are even close tobthat combination of size, speed, strenth and sheer athletic ability.
I wouldn't have a big problem taking a QB in theory, particularly with the situation we are in, with several other high picks. In practice it, as you say, gets more complicated, and you do have to factor in the situation with Tua. You are almost gauranteed to lose value with one or the other. In the long run, the team may possibly be better off, but that gets into crystal balls and tea leaves. It would come down to does management feel Tua can be "elite". Do they feel he will be above average, and is that acceptable? As you know, there's no gaurantee another guy will be elite either. Is it worth the investment to double down on finding elite? You probably remember, I was a proponent of a more prototypical sized QB before the draft, but now whats done is done.
My current view is that even though I see the same physical shortcomings that I originally worried about, I think giving Tua another year is the best course.
The rest of the team has to continue to be built either way.