I really don't think there's anyone necessarily to blame. You can't train a fighter to be mentally tough, to be able to focus in the moments when the pressure is the highest, etc.
I think it's something you either have or you don't.
It's not just athletes, but people in general. Some people, when the pressure is highest, they can focus more than ever. Others crack under pressure. That's just the way it is.
Some fighters have intangibles, other don't. Zab has absolutely none. That's never going to change, in my opinion.
He's always going to be a front runner who falls apart when he's seriously challenged.