I still remember that 4Verts interview where he talked about going to higher ups about wanting to really fix the O-line and their response was something like "Can we put that on the back of the box?" (in other words, is it "sexy" enough to market?). You could even sense the frustration in his voice just talking about it.
Saying he wasn't a franchise guy is unfair. If they went to him and said aright, Rex, we're going to give you all the resources you need to fix franchise, I truly believe he would have done so and he would've done a fine job... but like you said, if he wanted to keep his job, he had to embrace
their vision, regardless of what his was for it, and I can't blame him for that.