Rex might have wished for a longer deal, but the one-year extension is a clear indication to me that Rex wasn't willing to bend to Idzik and allow his GM to replace his defensive coordinator.
I can understand why Idzik would want someone he's more familiar with in the DC chair, with a head coach the front office has agreed to keep on for 2014 but might have some longer-term uncertainty. Idzik could be over-reaching. Allowing a head coach to choose his own coordinators and coaches seems reasonable.
Idzik could have made his play, but after agreeing to a one-year extension Rex appreas to be betting on himself and his players in 2014. Even so, we're sure that John Idzik will be scrutinizing the play of Dennis Thurman's defense in 2014.