Beating myself up about this one...

But I got to thinking, how could you not have seen in your peripheral vision the batters attempt? If you were keeping your head still and moving only your eyes, you should have seen the shoulders move.

Did you turn your head with the pitch? If you don't know, you should really have somebody keep an eye on you to see if you are moving your head with the pitch and put an end to that bad habit in a hurry!