which part of you disagreeing with? that the Colts offense is worse now than it was 2 years ago? I think it certainly is, but that 2004 offense was one of the best in football history. I find it hard to believe that teams weren't playing a lot of nickel and dime back then - or if it was the case, it was b/c the running game back then was too good to allow this.
Re: the defense, they have lost a few key players, which must be hurting them. there is now way this defense is as good as it was in 2004. it was ok then, bad now.
edit: I'm not completely in love with DVOA, but it attempts to isolate offensive performance from defensiv, which traditionally stats really don't do. you can look at the 2004 Colts
here and this year
here