As much of the reason as any other.
It's been well documented that this team was FAIL coming down the stretch of the season, and in the stretch of games. Everyone has their theories, including that a rash of injuries was too blame, losing Ben to injury, poor team discipline, poor game-day coaching, lack of leadership, lack of talent in key spots (running back, back up QB, O line, D line).
But I think I have the factor that is at least as critical as the above list.
"Fatigue makes cowards of us all."
No matter how much desire you have to win, if you are winded and spent coming down the stretch of a game, or season, you can't will yourself to win, because you can't magically get over fatigue.
Jimmy Johnson said it, but I don't know if it was his original quote. But once thing Jimmy ensured was that his teams WOULD NOT lose because they were fatigued. They may lose for other reasons, but getting winded would not be one of them.
I believe that is one of the major reasons why we folded down the stretch. Just look at some of the visible eye tests and you will find evidence to support this: Hampton, just more overweight than ever. (I know NT need to carry some extra LBs, but he has taken it to a weight that is counter-productive.) Woodley was obviously too heavy to play at his top level of play - his weight went up, his production went down. Don't tell me they aren't related. Colon, per usual, got hurt, and having to carry around an extra 40 Lbs - at least - could have caused his body blowing apart. Even Troy, admittedly coming off a non-ending injury, came back too heavy to play well. He could have been doing things to partially stay in shape when he was off, like swimming or something that wouldn't put stress on his calf. But, chose not to, and, apparently, we had no coaching staff to keep him in line in that area.
Oh, and least I forget, Dwyer was so out-of-shape, that the only back we had who could make a difference and give us a decent rush production, could only manage to stay in a game for two consecutive plays and that had to ask to come out of the game. Gee, I'm mot sure, but Bettis could play for a lot longer than two consecutive plays, as could every decent RB to ever play the game. The fact that the coaches allowed for Dwyer to be this winded that easily makes me conclude that our staff simply didn't demand that players get in the shape needed to win. If Jimmy Johnson was coaching this team, THAT would never happen. With Tomlin, who has grew a gut himself, we see a team where fatigue has made cowards of them all. Where was the leadership that DEMANDED players get in top shape?
This is a manifestation of the poor discipline problem, and I believe it had more to do with our late game and late season losses than anything. If they don't address this, nothing else will really help. I hope Art 2 demands a major emphasis on this area. Run this team until they are among the best-conditioned team in the NFL. If not, enjoy more FAIL.