Here's my guess. One of them was a pro..but was such a not flashy player he might have been missed. That's Kerry Kittles of Villanova. Incidently he was recruited from St. Augustine High School in New Orleans, to 'nova an Augastinian Brothers school.
The other two were I think both classic wide body "college centers" who were great college players were the wrong size to play that position in the NBA. I know one of them came from former member Boston College but I'm not sure if it's Danya Abrahms or Bill Curley. i think it's Abrahms because I remember hearing it mentioned on a telecast that he was having health difficulties and I think he was referred to as "a three time all big east first team selection.
The other "college center" I know just because he was one of my favorite players and that's Villanova's John Pinone. He came to nova from Connecticut and graduated in 1984 the year before the "perfect game" that beat Georgetown for the NCAA title. He was 6'7" could not jump over the saturday papers but was so clever with the ability to pivot use pump fakes and his wide body he found ways to score against anyone. His strength and toughness under the basket was a perfect compliment to Ed Pinckney for the 3 seasons they played together. He had a long pro career mostly in Spain and may have been a league MVP there. Thanks Marco and forgive me for the diatribe. There are lots of happy memories in there