Don't get it twisted -- Professor says the Beard's shake was "one of the best of the season, for sure" ... but to get an A+ in his class, you gotta drop fools with Allen Iverson-level sauce. Speaking of A.I., Grayson told us whether or not Iverson's his pick for GOAT NBA crossover artist ... and who he feels is the best in the game today (and trust us -- it's a shocker).