WALTHAM - Jim O'Brien officially enters his second year as head coach of the Celtics today. He looked back briefly yesterday on what a year it has been.


''I don't think it's been a fast year,'' he said following practice. ''Somebody asked me [Monday] night in dog years what it's been like. I said it seemed like a dog year, about six or seven years long. It seems like I've been here for a long time.''

Asked if he thought he had changed, other than having a bigger bank account, O'Brien said, ''I don't think you can change too much. I'm almost 50 years old [the big day is Feb. 11] and I've been doing this for a long time. Hopefully I'm not different. I'm probably a little bit older, a little more beat up than last year. I get less sleep. But as a person, I think I'm pretty much the same.''