I read in one of my management books that you do not want to work for a nervous boss. And you definitely don't want to be the one making the boss nervous.
Jerry really put himself behind the eight ball when he signed Garrett to the long term contract last year. Jerry was bidding against no one for Garrett's services. Jerry could have offered Garrett a one or two year extension after last season. No team was offering Garrett squat. One fluke season clouded Jerry's judgement along with his friendship and liking Garrett. Jerry gifted that contract to Garrett. Jerry also made the same mistake with Linehan and thought he was better than he actually was. Turns out Romo was 95% of the tactical brains behind the coaching and Garrett and Linehan just rode his coattails.
I'm not sure what Jerry can do at this stage other than eat Garrett and Linehan's guaranteed contracts. Probably around $30M overall. Jerry has enough money to just write it off since he makes around $250-300M per year roughly from the Cowboys. Perhaps there are ways to make Garrett and Linehan unhappy enough to just leave. Maybe giving playcalling to someone else, stripping Garrett of time management during game time etc.
Perhaps making someone an assistant head coach (wink wink) and treating that person like a head coach during meetings.
Maybe Jerry just wants to light a fire under the inept offensive coaches Garrett and Linehan have been this year. There has been no creativeness or ingenuity at all from the Cowboys for a long time. Ray Lewis said the Ravens knew exactly what the Cowboys would do several years ago. Bellicek even said this year that the Cowboys focus on execution and do nothing to make you guess. Been that way for years and years and has gotten worse under Garrett.
Garrett and Linehan went conservative and closed the playbook up when they should have opened the playbook up and got creative and played with a nothing-to-lose mentality.