By Chris Mannix Boston owner Wyc Grousbeck and Brad Stevens declined to explain the details of Udoka’s suspension. Wyc Grousbeck looked shaken. Brad Stevens, too. Hours after the Celtics announced a season-long suspension for Ime Udoka, an unprecedented punishment for what the franchise termed “a violation of team policies,” the two most powerful men in Boston’s organization struggled over the course of a 28-minute press conference to explain why Udoka was no longer a part of it. “It was a long, thorough process,” said Stevens. “Obviously it’s been a hard time.” The Celtics issued a terse, thr…