NBA Star Jaime Jaquez Jr. Raves Over Cooper Flagg's Game, 'Incredible Talent'

It's time to start buying into the Cooper Flagg hype if ya haven't already ... 'cause NBA star Jaime Jaquez Jr. tells TMZ Sports that after playing with the phenom this summer, he's the real deal. Flagg -- the No. 1-ranked H.S. player in the nation…