[Mike Simonds]

What you are describing is a block below the waist.

Blocking below the waist is only allowed under the following conditions:

1. By offensive and defensive players who are on their line of scrimmage and in the free blocking zone at the snap; and
2. The offensive linemen must be stationary at the snap; and
3. The block must occur in the zone; and
4. The ball must not have left the zone.

The free blocking zone is an area 4 yards on each side of the ball and 3 yards in front and behind the ball at the time of the snap.

The only time A82 can legally block B53 below the waist is if A82 and B53 meet all the requirements listed above. Otherwise its an illegal block below the waist that carries a 15 yard penalty.

From how you describe the play, it sounds like this is an illegal block by A82. I assume he is lined up more than 4 yards away from the center at the snap. Also, I believe SAM is your strong side linebacker so does he line up over the tight end? If so he may or may not be in the zone and on his line at the snap but if A82 does not meet the requirements outlined above then A82 cannot block B53 below the waist. Both players must meet the requirements.