WALTHAM — It’s been a recurring theme of the first week of the season. The Celtics  need more out of their bench — much more.
Doc Rivers  underscored that after open practice for special guests and clients on Tuesday. Rivers has told his team he’s not going to lean on Kevin Garnett  for more minutes when he’s already trying to conserve the big man for an 82-game season. Rivers hinted the same could be said for Paul Pierce  and Rajon Rondo , though he feels he has some more wiggle room with them.
“No, no, I’m not going to let him do more. I’m going to play Kevin the same amount of minutes,” Rivers said. “With Paul, Rondo you can go anywhere but if we can’t win with him off the floor, we just won’t win. And I told our bench that. We’re going to play the minutes that I’m giving them. The bench will play the minutes they should get and if they’ve got to do something or we just won’t win. It’s that simple.”
Garnett is averaging a reasonable 29 minutes a game in the first three games. Pierce is at 35 minutes and Rondo is playing 41 minutes per contest. Rivers has not yet seen the consistent production he would like from Chris Wilcox , Brandon Bass  and Jeff Green  but he feels it will come.
“Not yet but when you take Kevin out, you’re not going to get Kevin,” Rivers added. “That’s why he’s on the bench. But I don’t think that’s been an issue. When he’s been off the floor, like last year, when he was off the floor, it had a dramatic [effect]. I don’t think that’s been the case so far this year at all. I think the guys that have come in have tried to do what they should do. I think the other guys with him have to do more.”
Tuesday’s practice featured detailed instruction from defensive guru Mike Longabardi, who was teaching trapping principles and defensive rules within the system, especially important to the newer players, like the three rookies and Jason Terry  and Leandro Barbosa .
“Today was just a practice,” Rivers said. “It’s easier here because it’s in your natural surroundings. It was a good practice.”
Rivers again preached patience when talking about the newer players picking up the defensive scheme.
“We’re getting it,” Rivers said. “It’s just going to take time. I thought we were a lot better today. We’re working a lot of principles and tendencies. Offensively, it’s just moving the ball. Defensively, just running the coverages and talking. It just takes time.
“There’s no date,” Rivers added when asked if there’s an expected time by which everyone should be on board. “Every group is different because if one guy doesn’t get it, it brings the whole team down. Every year, it’s a different group. There’s no expiration date on anybody. It’s just takes time.”