His throwing mechanic combined with his throwing velocity makes it so he has a very small margin of error. A little bit too high of a release and it sails, a little too low and its in the dirt. However, in the right angle, and only the receiver is gonna get it. There is little leading to the reciever, so very little a safety can do to get in the lane to pick it off. For those who know the term, his throws are more Hit-Scan than Projectile.