I agree with you that 4 is probably too high for LTs today, pre pro days and combine. I am really leaning BPA at this point, but let's assume they want Campbell at LSU or Banks at Texas just for this exercise. They have them marked at 7-9 for either/both, but can't get a willing trade partner to move back into that slot, and then drop to say 11th, where they miss out on both. To me, it's better to take the player at #4 if you decide he's the "gotta have him" player, even if he's slotted to go a tick later in the round.
I'm really coming around to
@One-If-By-Sea point of view and go BPA in this draft. They have a lot of holes. I wouldn't take a QB if one falls to #4, but everything else is pointing to take the best guy, because you probably need him.