When does the U blow his whistle?

[BktBallRef]

Originally Posted by Line_Judge

I am guilty of the late whistle! I am a bit gun shy on the IW!

Which is why if I'm 1000% sure
1- the runner has the ball,
2- his forward progress is stopped (been shoved backwards 3 or more yards)
3- and the wings can't see the ball

I will whistle that play.

I've just seen too many times where the whistle should have been blown but wasn't, the runner was stripped of the ball. That's our fault.