The run game engages your biggest, hopefully baddest players: your linemen. Linemen don’t want to drop into pass protection for 60 snaps. They want to maul people. When they maul, the defense gets mauled and gets tired of being mauled. And then the infighting begins and the defense loses its self respect because nobody wants to stand there and get their bottom kicked play after play. You want to practice Sun-Tuz and sow seeds of division into the opposing defense? Run it down their throat for a few quarters.
Staley gets the mentality and fatigue element that the run game brings. Like someone said in this thread, if only McVay would listen.
We Not Me