i dont know if its the qbs as much as the rcvrs dont know how to run it either. if rcvrs run it correctly and use their bodies you can create huge passing windows, but most dont they just hope the throw is perfect.
I disagree if you have the timing and WR/QB to pull it off it is almost unstoppable. Look at all of AJ Green's TD's this year that's the main pattern in the red zone he runs. Barkley is very good at it in the college level as well. The fact that ASU did it with there smallest reciever on the field makes me question the reasoning if it had been to a 6'2 WR that's a TD.