How did the C's go 27-27 down the stretch last year with a healthy Perkins? He wasn't just in the locker room, and with the team; he was actually on the court and contributing to games then.
The team was injured, and was admittedly coasting at the direction of Doc and the front office. The goal seemed to be to get healthy before the playoffs, and the lack of effort was visible on the court.
This year, it just looks different. The effort seems to be there (from everyone but Rondo, at least), but the results have been largely terrible. Doc is calling the team out, the players are getting frustrated, the team lacks an "identity" for the first time in four seasons, and the chemistry just isn't there. Coincidentally or not, this slide seems to coincide with the trade.