How did the Pittsburgh Steelers go from winning a Super Bowl, starting the season 6-2 and being labeled the best team in the NFL after beating the Denver Broncos on the road, to the team that lost to Kansas City, Oakland and Cleveland in one disastrous stretch? "If somebody knew that answer, I think we would be doing better" said James Farrior. "We have the same team as last year," Added Hines Ward. "How do you win a Super Bowl one year and not make it and lose five straight the next year?" Source: Tribune-Review
I would say lack of aggresiveness without Troy, as well as horrible offensive playcalling and poor offensive line production.