That 75 yard run play was a bad play by the Seattle coaching staff as there was only one middle linebacker on the field for it, due to the Nichol defense.
Tatupu got blocked and there was noone else around on it.
Coaching is part of the team effort. Holmgren owns the loss as much as his team. Or, to put it more correctly, Cowher's staff saw a weakness and exploited it to devastating effect.
Or do you think Tatupu calls his own defenses and runs the practices?