I think this misunderstands how Gailey coached.
He knew he had a DC who could make things work. Provided, that is, that the O side didn't turn the ball over. He was a pro coach, basically, and had a strong aversion to mistakes. (It's different now in the pros, but not then.) People always say that he didn't develop Reg, who had great talent as a QB, because his numbers - particularly completion % - went down over time. Actually, I think he did. What he did was tell Reg that if he wanted to stay on the field he would have to make safer throws and be willing to throw the ball away if he didn't see an open man. When he was a frosh, he flung the thing all over the place and had a decent completion % and a lot of TDs. He also had more interceptions then TDs: a major no-no for a coach like Chan. He wanted to play the games close and win with D. My favorite Chan game - and one of my all-time modern favorites - was our 2003 7 - 3 win against Maryland in Fridge's first year there. We got ahead, played good D, and sat on the ball like a slug for the whole game. And Reg kept under control.
Well, that was then; this is now. We can't expect with modern Os that we will be able to win a game like that again. I expect us to play better D next year - we were ok this year, given the injuries - but unless we perk up the O, we will be in deep do-do.