It’s put-up-and-grow-up time

Less than two weeks before the start of the NBA season, and Andrew Bynum laughs like he’s still on summer vacation, hopping around the center of the locker room like a giant child.

Then you look closer and realize that, when describing the key to the Lakers’ season, those words no longer go together.

He’s no child. He’s all giant.

Have you seen him? The kid who wandered into the Lakers’ locker room three years ago has become a man -- huge biceps, broad shoulders, no longer gets lost in Shaq’s locker.

In nine days, he’ll be 21 years old, entering his fourth NBA season, which is exactly how long it took another Lakers high school draftee to win his first championship, a guy named Kobe Bryant.

For Bynum, it’s graduation year.

Which doesn’t give him an excuse for senioritis.

This is not a time for him to be late for practice, which happened last week.

This is not a time for him to be tentative with his rehabilitated knee, which has happened during training camp, Bynum yet to show the Lakers the full-court energy they require.

More than anything, this is not a time for his agent to be publicly popping off about the Lakers giving him a new contract.

A new contract for what?

He might be the key to the Lakers’ championship run, but in three seasons he has played only about a month’s worth of important games for them.

Yet last week his agent David Lee squawked in this newspaper about the Lakers refusing to seriously negotiate a new deal worth $85 million before an Oct. 31 deadline.

“I just don’t get it,” Lee said to The Times’ Mike Bresnahan. “I do not understand certain things that happen.”

Understand this: The Lakers have no idea whether Bynum will fully recover from the knee injury that cost him two-thirds of last season.

“I think he’s going through a re-acclimation process still,” Coach Phil Jackson said Saturday before the Lakers’ 108-104 exhibition victory over Regal FC Barcelona. “Some of it has to do with finding out how much he still has to physically recover to get back to that position where he was when he left the game last January.”

Understand this: Even if they don’t sign him by Oct. 31, they can match any other team’s offer next summer when he is a restricted free agent, so if they want him they are guaranteed to have him for at least two more years.

Why should they do something now?

“Andrew has taken everything the Lakers have thrown at him, including criticism,” Lee said. “He doesn’t do anything to respond other than go on the court.”

Except when he’s missing 110 of the Lakers’ 279 regular-season and postseason games since joining the club.

And what exactly have the Lakers thrown at him, except the best attention from trainer Gary Vitti’s staff and extra work with every coach and everything else he needs to be the best?

OK, so Bryant wanted him to be traded. When Bynum proved himself last year, Bryant was the first guy on the bandwagon.

It’s time for Bynum to prove himself again.

Allowing his agent to make such a stink about something so senseless is not the sign of someone who is focused only on his comeback.

Bynum reiterated Saturday that he approved those comments.

“I knew what he was going to say, I had no problem with it,” Bynum said. “But I also know that as long as I play, then everything will be fine.”

So play. And tell everyone in your circle to just watch.

He has already learned that, while Lakers management is used to hearing this sort of agent blather, the fans will pounce upon it, especially in a season when nothing less than a return to the NBA Finals will be enough.

When Bynum fumbled a pass Saturday at Staples Center, a fan stood and shouted one word.

“Contract!” he screamed.

When Bynum was beaten around the basket, another fan shouted out a challenge.

“Show me something!” When the Lakers were called for three seconds?

“That’s on you, Bynum!” shouted a fan.

At times, moving under the basket, slicing through two defenders for a layup, Bynum looked good.

At other times, struggling to catch up with some dude who looked like he was 50, he looked winded.

He had his first alley-oop dunk in a game situation since camp began. But he also had some dumb fouls that came from being out of position.

The giant believes he will be in playing shape by opening day.

“I should be there,” he said.

The coach believes that, despite Bynum’s tardiness last week, he truly is working hard and not distracted by the contract stuff.

“I really think he’s focused on basketball, I think he’s doing fine,” Jackson said.

Bynum is a good guy. He works hard, everyone likes him, his presence in this town could one day be as big as that new body.

But 85 million dollars?

How about 82 good games?

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Bill Plaschke can be reached at bill.plaschke@latimes.com. To read previous columns by Plaschke, go to latimes.com/plaschke.