Nenad Krstic and Jeff Green, since joining the Celtics on Feb. 25, have essentially spent their time in a mobile classroom. They've attempted to blend in on the run, from city to city, almost never with an opportunity for extended practice time. It's probably not a surprise, then, that the Celtics bench underperformed during their first-round sweep of New York. The Celtics coaching staff seemed as puzzled by Green's role as the forward himself, as he was swung between small forward, power forward and even a little big guard. Now that they may have realized he's a so-called 3, and nothing but a 3, Green may be making headway. Krstic has slipped so far off coach Doc Rivers' radar, he has strictly become a first-half player. His immediate playoff future is a crapshoot, especially if Shaquille O'Neal returns. He's a little confused. "Not really," Krstic said of understanding his role. "I play three minutes and sit down. You start to get going. I don't need to score, just do something to try and help the team. But it's hard." Krstic's dilemma is reflective of the entire second unit, Green included. But in the case of the Serbian, his offensive game, and especially his specialty as a pick-and-pop option, has gone by the boards. "When I get four or five minutes or whatever, I just go out and play hard," he said. "Get rebounds, set a good screen. But I don't have a role offensively, like going in the post or pick-and-pop. I'm more defensively oriented.