why don’t more teams design plays to use the Umpire as a pick on a crossing route?
Not that Vele rubbed off the Umpire, but it certainly looked like he could have. Is there some rule that receivers have to be x yards away from the Umpire?
No rule. But the Umpire isn’t always in the same place – they’ll adjust their positioning based on the defensive formation, down and distance, or game situation. So planning on using the umpire as a screen won’t work that often because you can’t plan on them being in the same place every time.