It was many things last year, and I absolutely sense that effort was a big part of it. I can't really prove that, but it really seems that the whole competitive effort of the team fell off a cliff. Actually, one of my standard complaints about FIsher has been that he was lazy and evolved a slack team culture.
But, the questions obviously asked for the top, key factor. And I think that, at the core of everything else was Fisher's inability to develop a passing game. The defense certainly had a lot of ability. The point of the question was that the running game did well in '15. STs were good.
But what never, ever worked was the passing game. That was our Achilles leg--much more than a heel. We simply could not compete with the league without a passing game. We couldn't move the chains, stay on the field, or score points. And the debilitating awareness of that reality rotted the team's will. How can you blame a defense, for example, of sliding from top intensity when it realizes that, once again, the offense will not carry its share of the load?
Honestly, I think just about everything comes back to the failed passing game. That's just my sense of the core dynamic.