Crack Back Block

[Forksref]

2-17-3,4 Offensive lineman must be on the line of scrimmage and in the zone AT THE SNAP in order to clip or block in the back. (my emphasis)

[seanireland]

Originally posted by CoachG6
Guys

What constitutes an illegal crack back block? I've seen plays where, at the snap, a split end moves down the line toward the ball and blocks an unsuspecting defensive end. Under what circumstances is that legal?

Thanks
Coach G6

Don't see any mention of motion, but let's say he is in motion. He will have to be five yards back because he didn't clearly set as a back for one second. Otherwise, he starts on the line runs to the defender and plows him with a legal block. Perfectly legal. If he is in motion five yards back, same thing applies. ENZ??? What has that got to do with it? We either have a legal block or we do not. Legal blocks in the back occur in the FBZ or when a defender who has a right to make a tackle blocks a blocker in the back in an attempt to tackle the runner. Let's not forget that legal block in the back. Motion or not, the offensive guy can not block in the back, clip, illegally use hands, or chop block.

[BktBallRef]

Originally posted by andy1033
This is an illegal shift if the split end is not 5 yards behind LOS at the snap.

How many times have you ever seen this called?

[Bob M.]

Originally posted by andy1033
This is an illegal shift if the split end is not 5 yards behind LOS at the snap.

REPLY: Not that it makes a difference, but it's actually illegal motion. and I've only called it (as a LJ) once in 24 years!