Remember, this was a political coup by the left urban Democratic elite centered in Portland. It involved the Willamette Week and the Oregonian and a bunch of upper level Democrats. Kate got one of the prizes and the "appropriate" people moved up.  

Kitz did not watch his back, and Cylvia became a serious political liability in a way he did not fully grasp. So they took him down. It required some illegal theft of State information, but Kate stepped in to clean up after that.

Kitzhaber was a centrist, and he looked for compromise and toward the good of the State as a whole. The urban elite Dems no longer need to compromise. They no longer need to be concerned about much beyond the north stretch of I-5 in Oregon.