"So who is Tom Thibodeau, and why has he been an NBA assistant coach for 19 years? And why, as Boston's defensive coordinator, did he not get a single interview for a head job after the Celtics won the championship in 2007-08?"We've talked about that and I don't know the answer," Celtics coach Doc Rivers was saying yesterday. "Sometimes, fairly or unfairly, you get labeled as an assistant. In Thibs' case, it's unfair."The 76ers apparently see more in Thibodeau, having placed him on their list of candidates for their vacant head-coaching position, although Rivers said he was unaware of when an interview would take place. Sixers president/general manager Ed Stefanski has already visited with former Sacramento and Washington coach Eddie Jordan, Dallas assistant Dwane Casey and Los Angeles Lakers assistant Kurt Rambis.The Kings must see something, too, having expanded their search to include Thibodeau and Rambis.The public basically knows Thibodeau as the guy sitting next to Rivers on the Celtics' bench; Celtics' assistants are not free to speak on the record with the media during the season. He did meet with the Kings when he left Houston after '06-07, before he landed with the Celtics."I'd say to general managers, give him a chance, see who he is," Rivers said. "It's one thing to see him sitting next to me. You know me, you don't know him."Sixers fans might have vague memories of Thibodeau as an assistant for two seasons in Philadelphia during the John Lucas era in the early 1990s. Since then, working with Houston, New York and Boston, he has had 15 teams finish in the top 10 defensively."He's terrific, with unbelievable knowledge," Rivers said. "He knows the game, is a great teacher. And he knows more than defense. In some ways, he's so good defensively, people overlook his overall knowledge. Thibs is our defensive assistant, but has offensive input. Armond Hill is our offensive assistant, and he has input in the defense. But as good as all of Thibs' schemes might be, when you lose Kevin Garnett [for most of the season], somehow it doesn't look the same. Thibs' isn't Buddy Ryan. He knows so much more about basketball."Rivers spent time with Thibodeau on Tuesday night, helping prepare him for the interview process."