When Did This Rule Go Into Effect

[ajmc]

Your example sounds like the QB is a "Runner", and the TE still poses a very real threat to block the LB should the QB decide to continue running. Both the QB and the TE may know the objective is to pass the ball, but until the ball is thrown, the LB is guessing and is allowed to defend himself and ward off a potential blocker.

Unless the TE has moved to where he is no longer a potential blocking threat, which is determined by the judgment of the covering official, either contact sounds legal.