Here is my theory and many have touched on it
Dez is more important for the offense. During the Packers game they showed replay with the corner and safety bracketing Dez. There is a reason why Williams and Beasley came on all season. They had openings due to Dez.
Murray was a stud but he was never healthy until this year. Then we saddled him for 490 carries...120 more than h 370 threshold...and it worked. Problem is history has shown guy go down after that amount of carries. He may do decent but is 1000 yards good enough these days? We have a line and run a system. We don't do a pure zone scheme like the Broncos and then Texans did but we run a similar enough look where one cut runners work better like Murray. I believe with that line we can find a back that fills the hole, still gives us cap room and makes the offense work.
I'm actually pretty proud of Jerry for taking a cap friendly stance.