Diabate was a top 10-15 recruit out of HS. The difference in NBA potential between top 15 and top 100 is immense.
Kevon Looney is 6'9", Robert Williams is 6'8"
Those two started at center for the teams that played for the NBA championship
Clint Capella is 6'10", Bam Adebayo is 6'9"
I'll stop looking after the first four guys I thought of.
Also I'm not saying Pikiell would say he'd NEVER play the 4, just that he's not ready yet. Like Cliff didn't shoot 3's his first two years and now, supposedly, he's going to.