Depends. If Sestak was offered (as is rumored) Sec Navy, then it goes all the way to the top. Sec Navy is one of the Joint Chiefs and thus directly under Dumb0’s command. And by directly I mean like sitting right across the table from him.
No way any credible offer like that could have escaped the notice of the CinC.
Secy of the Navy is a civilian position, not a member of JCS (uniformed military).