Lot of things.
1) Schedule got harder, we're playing better teams
2) Weather got worse we play a system that's very dependent on good weather to throw the ball, with a QB that despite being from Iowa is not good in bad weather.
3) Defenses have adjusted. They seem to have figured out when we're going to run the ball so they can load up against the pass, take away our pet routes, and still defend the run because they seem to know when it's coming.
4) Since Highsmith got hurt the ST suck. I know you hate to risk starters but we need to put more starters on kick coverage this is getting comical how bad the kick coverage is.
5) The OL has collapsed. Just like having a QB throw over and over apparently tires out the QB, it also apparently wears out the OL since the pass blocking has gotten worse and the run blocking has too.
6) Coaching, Whiz is either sand bagging or he's gotten very complacent. When he declined that penalty yesterday and then watched Cassel run for 16 on 4th and 11 I almost had to laugh. as soon as we declined it I said what the hell? I posted on the game thread why decline, before the next play had been run. What NFL coach wouldn't rather have a 3rd and 26 in the snow from about midfield instead of a 4th and 11 from about the 35 knowing the Pats were probably going to go rather than risk a FG or punt? That was such a bad decision we were going to lose anyways but that decision was like he just didn't understand the game.