Yesterday Rondo was waiting to sign a piece of paper that would make him much more than a kid. It would make him set for life, which at 23 can be a dangerous thing. The five-year contract extension worth $55 million in guaranteed money would wed him to the Celtics until 2015, at which time he would not be a kid. With any luck at all he'll be a 29-year-old point guard who has become the face of the Celtics .

If that happens he also will be a bargain. Frankly, if you take a step back and forget all the immaturity talk that was flying around in recent weeks and look at what he's done, the numbers sound like, well, maybe not a bargain but certainly what Rivers said of them yesterday.

``He's earned it,'' Rivers said and then thought back to his days coaching McGrady and Miller.

Much has been made of Rondo's supposed immaturity, which flashed itself again Sunday night when he got into what seemed a game-long schoolyard beef with New Orleans' Chris Paul. Over what, nobody knows, but Rivers didn't care. It had to be stopped, so he spoke to Rondo. After the game, the guard was summoned to the Celtics training facility in Waltham to sit with president of Basketball operations Danny Ainge for what Rondo called an hourlong father-and-son chat.

Can't speak for Rondo, but an hourlong chat with my father would have been a pretty one-sided conversation. Maybe it's different when the father figure just OK'd a $9 million-a-year raise. What's more important is that Rondo is a very good young player on a very good old team. Last year in the playoffs he nearly averaged a triple-double (16.9 points, 9.7 rebounds and 9.8 assists) during a time when he supposedly was exhibiting these maturity ``issues.''

Is he a bit immature? I would hope so. At 23 what's he supposed to be? Your Aunt Minnie?

Maybe occasionally Rondo does things on the Basketball court that make Rivers scratch his head, but that's what the Post-it notes were for. They were a reminder Rivers no longer needs that with youth comes arrogance, self-confidence sometimes spilling over to egoism and an occasional lapse in judgment.

When millions of dollars are involved these are things that can blind the public to what a young player really is. Fortunately, they have not blinded Ainge or Rivers. What they see is a kid who, while not perfect, has earned the raise and the security he just got.

It is up to him what he does with them, for things come with that kind of money, among them heightened scrutiny and jealousy. Surely there will be moments when the public shakes its collective head and thinks, ``Why'd he do that?'' Maybe they will use harsher words on the radio to describe the petulance of youth.

Fortunately Rondo won't answer to them, although he will hear from them. He will answer to Ainge and Rivers.

``I'm fine with his maturity,'' Rivers said. ``He's far more mature than his age. He picked his job so don't feel sorry for him, but he's growing up in front of everybody.

``I know I was in the league at 24 and I don't know what I was doing but I know it wasn't anything good. I was lucky. I had the oldest team (around me) in the history of mankind. Tree Rollins, Gus Williams, guys who would say after a game, `Keep playing young man. It's not as bad as you think.'

``He's 23 years old. He hasn't reached his prime. He hasn't scratched the surface. He's stubborn, but that's a good quality sometimes. You've got to believe in yourself all the time. The problem is he's playing on a world championship team so you saw all his warts and all his good things.''

Wisely, Ainge, Rivers and Celtics ownership also saw what Rondo really is - a kid who can play.

- rborges@bostonherald.com