Rickman with the W once again!
Alright, this is a pretty fascinating question, once you dig in a bit. . .
* While Griffith may not have been a Top 50 all-time player, he has a strong argument for #1 basketball nickname of all-time: Dr. Dunkenstein
* The five other players were: Magic Johnson ('79), Isiah Thomas ('81), James Worthy ('82), Hakeem Olajuwon ('83), and Patrick Ewing ('84). While I'd argue that Worthy was overrated as a Top 50 talent, his teammate on that '82 team was not. Hakeem also had a Top 50 teammate in Clyde Drexler.
* cjbfbp has already alluded to this, but it was just an astounding period of talent in college basketball at that time. In addition to the players already mentioned above, you have Ralph Sampson Jr, who was perhaps the most dominant college player since Kareem/Walton, Larry Bird, Barkley, Karl Malone, McHale, and Stockton among Top 50 players who played college ball in these years. (and Dominique and Mark Aguirre and Buck Williams and Ro Blackman and Terry Cummings and many, many other very good to great pros).
* There was one other stretch of five Top 50 players in a six year stretch, arguably a better group, from 1955-1960 (actually, not really arguable-it's a legendary group): Bill Russell ('55), Wilt Chamberlain ('57), Elgin Baylor ('58), Jerry West ('59), and Jerry Lucas ('60 and '61). I didn't think anyone would figure out the non-Top 50 guy from '56--Hal Lear from Temple. Interestingly, only Russell and Lucas (in '60, not '61) were on championship teams. That was a pretty common occurrence back in the day, but after '66, there's only been one player chosen as MOP whose team did not win the championship-Hakeem in '83.
* Since '84, there's been a marked difference in the level of talent that's won the MOP award-I'd argue only Anthony Davis would be in the conversation for a Top 50 NBA talent among the winners (with Carmelo as a Top 100); in fact, after Davis in 2012, the talent has been pretty marginal, at least for the pro level-Donte DiVicenzio would be the top player, followed by Tyus Jones.