1. Ken Shamrock
Shamrock first left mixed martial arts after the Ultimate Ultimate in 1996, leaving to become a pro wrestler in WWE. When he returned in 2000 it was clear the sport had passed him by. Since that time his record is 5W-12L to go along with multiple failed steroid tests.
Probably the best example of how poorly Shamrock faired/is fairing since returning to mixed martial arts some 16 years ago, was his trilogy with Tito Ortiz. Shamrock dropped every single fight to Ortiz, and was clearly a level or two below Ortiz at that time.
