I've heard someone describe Sanchez as "unnatural" at the quarterback position. I can't think of a better description. While I've come respect Sanchez as a leader who bounces back from adversity, especially with the NY media, I am still astounded while watching him.
Many, many of his throws are just indescribably bad. He rarely hits the receiver where he should; the ball is always too high, too low, behind or ahead of where it should be. His accuracy numbers are up this year, but those are almost all on screen passes and some very accuracy-friendly receivers like Mason, Keller, and Holmes.
If anyone has played coordinated sports before such as football, baseball, or tennis, you'll know that your mind just naturally gets into a hand-eye coordination groove. It seems that with Sanchez, he just does not have that, at least at many times during the game. I've heard his hands are too small; perhaps that is the explanation.