Actually, Strzok rose to become the Deputy Assistant Director of the Counterintelligence Division, which is the number two position in that division...so not Dep Director of the FBI, but of a division within. Again, still. SES.
RedState thinks that Strzok was an SES “equivalent”.. I suppose meaning that he held a position high enough to be held by an SES employee, but he wasn’t one. Article here:
https://www.redstate.com/streiff/2017/08/16/unexpected-personnel-shake-hits-mueller-investigation/
The whole Senior Executive Service looks like it could be rife with abuse of power... something that really fills the role of the Deep State, a shadow government trying to subvert the elected government.