He is from Kansas, so that was why KSU. I'm guessing that job was more paper-pushing/adminstrative than he was hoping. Think he wanted to have more of a say in how the football team ran.
Rutgers was he last chance to be a full college football coach, with all duties including recruiting. He gave it a chance, and his body said "Jerry, it's time to stop". I don't think he had any ties to Rutgers or maybe even that staff, he was just an opening and he went for it and got it.
SIU was because they have roots and a lake home in that community, from his days as SIU head coach. Again, I guess it was too much admin and he wanted/needed more football "action"
VT I imagine was very similar to the Rutgers deal. He convinced Fuentes to let him be a non-recruiting, perhaps even not even coaching players, but could try to have some football "action" and say in how the team ran. And it worked for him. He could do it, and it was satisfying.
So the next step then, was to try to go to a program that he actually had ties to and wanted to work with, rather than just a random opening. TCU and Patterson fits that bill nicely. If it works for both of them, then I could see him staying for a while.
^^^ This is just my feeling, anyway. I have no idea how much truth or bits of truth might actually be here.