BJ is a pretty stupid QB, his IQ on the field is pretty bad and he has horrible accuracy. He only seems worse now because Holtz doesn't utilize him like Leavitt did in his first year, as a scrambler QB who could make plays with his legs instead of trying to be a pocket QB (which he sucks at). Holtz sucks as a coach, and BJD sucks as a QB, but Holtz is minimizing BJ's speed with how he uses him on offense.
Just a bad combo, because they both suck.