Basically, the wide receiver Mike Williams was pushed out of bounds, came back in, and caught the ball. Normally, you are allowed to catch the ball if you are pushed out of bounds as long as you reestablish yourself, because the push itself is an illegal contact penalty on the defense.

But since QB Josh Freeman was outside the pocket on this play, it was totally legal for the defender to push Williams out of bounds (illegal contact can only occur if the QB is in the pocket). As a result, Williams was not allowed to be the first player to touch the ball after going out of bounds.