When a DL gets the opportunity to sack a QB
just hold the QB in a bear hug and do not take
him to the ground, I bet refs are more inclined now
to call "in the grasp" than they were before.
For the Mathews vs Cousins situation, the QB is
about to release the ball, the pass rusher should
be trying to affect the release of the ball. the pass
rusher probably should be extending his arms to
strike the QB violently in the chest.
His extended arms will reach the QB faster than
his shoulder would, and have a better chance to
affect the release of the pass.