It's pretty difficult to win when you not only have to beat the other team, but also make plays to beat yourself. The culture of failure to me goes hand in hand in with not having situational awareness. Im sure a lot of us were thinking before the Leodis fumble on the KO against the Pats, whatever happens just dont get stood up, you know they are going to try and strip the ball. What happens, boom stood up, and fumble. How many times do you watch a receiver make a first down, espcially going across the middle and you say get down. Watch a guy like Welker, he does it consistently. Thats smart football. Or after you got the first down, have 2 hands/arms covering the ball. Or when its better to take a sack and keep the clock running, not get flushed out and fumble like JP did.
To me the culture of failure is real, and its combination of stupid play and poor coaching. If I'm Marrone, I devote entire meetings about situational awareness with film examples.