Allen Edwards, Heshimu Evans & Eloy Vargas are the three that come to mind the last 25 years or so. Edwards would have been a starter probably anywhere else in the country but he backed up Anthony Epps and Wayne Turner for his career at UK.
Heshimu Evans is the guy who didn't do anything great but did a lot of things pretty well. He was an important part of the 1998 title team, yet we remember Turner
leading us, Mills hitting the famous shot (first three in the game for him) as well as Padgett's three where he then turned around and ran down the court. Not to mention Jeff Sheppard dunking on the entire country that year. But Mu was a strong contributor who never gets mentioned when discussing that championship team.
The number of times I've wished we had a player like Eloy since our title team, I can't even count. Just a reliable big guy who can stand in there and let our star big man (Randle, WCS, Nerlens, Towns, Skal, Bam) get some rest. A PF/C with size who won't set us back and might actually contribute some. Not pick up stupid fouls or allow a bunch of offensive rebounds. This is why I selfishly wanted Humph to stick around because, while he's not as good as Eloy was (not yet at least), he had that same game, same size and served the same purpose.