The Boston Celtics have operated without a defined big-man coach in each of the past two seasons, but the addition of young bigs in rookies Jared Sullinger and Fab Melo was a primary reason that coach Doc Rivers brought Jay Larranaga on board and assigned him to the big men this year.

Now the Celtics have two big-men coaches: Larranaga and Kevin Garnett.

While Garnett has always taken young big men under his wing, that role has seemingly increased in recent seasons. Over the past three years, we've seen Garnett giving private lessons to the rookies classes of Luke Harangody and Semih Erden, and JaJuan Johnson and Greg Stiemsma, and, now, Melo and Sullinger.

At this point, you know the rules: The young player has to listen and be committed to applying what Garnett is stressing. If not? We'll let Paul Pierce sum it up.

“Well, those guys don’t stick around long. Just to be honest," said Pierce. "You have seen those guys, and they’re not around here, and you can see why.”

After the Celtics' second practice of training camp wrapped up earlier this week, Garnett herded together all the team's big men for a quick tutorial on defending the pick-and-roll, and -- more importantly -- the necessary volume with which to announce the opposition's intentions of running the pick-and-roll (as to alert the defender on the ball-handler).

"Kevin’s been phenomenal," said Rivers. "He’s had a big-man camp of his own [earlier this week] and he’s done it almost every day. It’s nice when you can tell the veterans like the young guys, you can see that."

As Rivers quickly pointed out, everyone on the team likes each other at this point. It's whether Garnett can maintain a trust in those young bigs, something that Erden and Stiemsma seemed to do in their time in Boston, which allowed them to grow into key roles.

Pierce hopes the younger players understand the luxury they've been given.

“Every team doesn’t have that -- a veteran leader, a guy that’s been around the block a few times, that’s going to really accept them, take them under their wings, and just give them that experience," said Pierce. "[Garnett]’s a great teacher. I mean, he’s one of the best to ever play the game, so when Kevin Garnett talks, as a young player, who doesn’t want to listen? And if you’re not listening, then shame on you, because he’s one of the best who’s ever done it.”