If you pay attention, QC helps you strafe around to seal a block...
http://goallineblitz.com/game/replay.pl?game_id=672831&pbp_id=5077688 Watch the RG strafe past the NT and seal the play side of the screen. He changes his blocking direction 180 degrees.
It also helps you pinball in a tangle of defenders, shifting your block as the HB runs past... taking out two blockers without needing a pancake...
http://goallineblitz.com/game/replay.pl?game_id=672831&pbp_id=5071480 Watch the RG shoot over to the SS right as the HB gets there and take him out of the play.