Williams made the comments during a radio interview with Charlotte-based 610AM WFNZ's 'The Drive' With Taylor Zarzour and Marc James.
"I think it's still up in the air but we're much much closer to having all of them back than we were last year," Williams said. "They are all enjoying school, they are all still hungry to do more and there is nobody that is a guaranteed Top 10 pick. ..."
Bullock, a junior wing, averaged 13.9 points and 6.5 rebounds per game, while shooting a team-high 43.6 percent from 3-point range in 2012-13. McAdoo, a sophomore forward, averaged 14.4 points and a team-high 7.3 rebounds.
Hairston, a sophomore guard, vaulted into draft consideration after moving into the starting lineup over the final 13 games. The Greensboro, N.C. product led UNC in scoring with 14.6 points on 39.6 percent from 3-point range.
None of the three players is considered to be a lottery pick by various mock drafts, while only McAdoo is consistently listed as a first-round selection. CBSSports.com currently projects McAdoo as the No. 23 overall pick in June's draft.
"We still have to continue going through the process, allowing those guys to make decisions and in my mind some of them have already been made just about, but we're going to wait until all three are done so we can just have one announcement," Williams said.
The NCAA's early entry withdrawal deadline is Apr. 16, one day after the NBA Undergraduate Advisory Committee's deadline to provide a response for potential early entrants.
The NBA's early entry eligibility deadline isn't until Apr. 28, however, meaning any underclassman that intends to turn pro early can ultimately make the decision 12 days after the NCAA deadline.