Apparently, he was asked by Jerry to take on both OC and HC duties and didn’t fight to keep the OC part.
https://www.usatoday.com/story/spor...rry-jones-jason-garrett-play-calling/1855621/
No, I don't know if you were not following the team back then or if you were too young or whatever but Garrett did not want to give up play calling.
Garrett would not even acknowledge to the press that Callahan was going to call plays despite Jerry making the decision immediately after the previous season. I'm not sure if Garrett ever really said directly that Callahan was the play caller but Jerry and Stephen not said Callahan was the play caller.
Last year Stephen said that looking back they didn't give Callahan enough support and that allowing Garrett to make the personnel decisions with regards to which offensive players were in the game undermined Callahan as the play caller.
There is a reason that Bill Callahan departed when his contract was over for the same job with the Skins despite Jerry trying to money whip him into staying. It was because he and Garrett were enemies after the year Callahan called plays.
Garrett begged Jerry to remove Callahan as the play caller after that year. Jerry told Garrett OK but only if we hire someone else because you (Garrett) are not going to do it.
The compromise was hiring Linehan who Garrett was basically allowed to choose.
Callahan went back to being just the OL coach for that year then departed the minute his contract was up. He tried to depart a year earlier but Jerry insisted that he finish his contract.