There's a huge difference between an all time starting 5 and the greatest 5 to have ever played. CJ Watson, Rodney Woods and Jordan Bone, maybe even Danny Shultz, are the best PGs, but Allan Houston, Lofton, Jimmy England, Mike Edwards, Mike Jackson, JuJuan Smith, and Tony White are arguably better guards. However, Bone still has a year and a half left. He could leave campus as the greatest PG to have ever put on a TN uniform.
Same deal at the 5. Boerwinkle is most likely the best true center... maybe Kosmalski the 2nd. But there are power forwards that were better. Reggie Johnson first comes to mind. Tobias, King, Ellis, Tyler Smith, and maybe even Widby would take that spot if putting the 5 best talents on the floor.
TN's greatest players have been forwards with a couple of shooting guards added to the list.