http://lubbockonline.com/stories/090905/pro_09090600.shtml
http://www.nytimes.com/2010/02/09/sports/football/09payton.html?_r=0
Mike Zimmer was a 4-3 coach, he was running Parcell's defense, but when Parcells left we had to bring in Phillips who could continue to implement the 3-4. This resulted in Zimmer being let go. We brought in Brian Stewart as the next defacto defensive coordinator. Stewart got fired shortly later because the defense was not performing. Eventually Phillips would be fired as well, and Garrett became head coach. Not wanting to call the 3-4 a failure, we hired Rob Ryan... two years with his complex defense, and we still weren't established as a dominate defense.
Finally Jerry said enough and we hired Kiffin and Marinelli.
You can certainly blame Jerry for the failings of Parcells and his decisions because he hired him, but most people would have said it was a rational move. The move to the 3-4, also rational given the nfl trend, and the head coach we had. Just because you make a rational move doesn't mean the results will be positive, and they haven't.
What people do though is blame him for the poor results, which I think are a bit unfair. As owner and GM his job is to make rational moves. Which I think for the most part he has made.
The move I have disliked the most, because it wasn't rational was hiring Jason Garrett in the first place. We didn't need an OJT offensive coordinator or head coach. Jason Garrett has certainly cost us some playoff berths. Of all the moves Jerry has made, I think that has been the worst and most irrational.