CLEVELAND — If the book on how to perfectly handle LeBron James defensively was found today, it'd be an instant best seller across the NBA. At this point, it remains relatively vague — even as he nears his 39th birthday.

James and the Los Angeles Lakers returned to Rocket Mortgage FieldHouse and defeated the Cavs 121-115 Saturday night. In this, his 21st season, not as much has changed with his game and the problems he causes opposing defenses as one might have thought a few years ago.

James entered Saturday night averaging 25.7 points, 8.1 rebounds and 6.7 assists per game. None of those are far from his career averages dating back to 2003. He's actually been more efficient, shooting 57.8% from the field (50.5% career average) and 41.4% from 3-point range (34.5% in his career).

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Teams used to have a clear game plan. In his early days — circa his first go-around with the Cavaliers — James was too lethal driving to the hoop. The idea was to almost play prevent defense and dare him to try a long jumper or, ideally, a 3-pointer. Over time, James took away that disadvantage as his outside shot improved.

The book on how to guard him has been altered over time, but it hasn't been found in its entirety, either. Teams have only been able to discover part of a torn page here and there.

"You continue to see how [the game plan] has evolved," said Cavs coach J.B. Bickerstaff. "There was a time where you could go under all of his actions and let him shoot behind-the-screen jumpers. Those things have changed. Obviously he's become a better 3-point shooter over time."

He's 13 months from his 40s. And teams are still trying to figure out what to do.

"It's something that over this long of a period of time that you just have to marvel over because again, we haven't seen it done at this level," Bickerstaff said. "I think the sports medicine and attention to the bodies and health and nutrition has changed, but to see a guy doing it at this level for this long, I don't think we've seen it."

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In a way, James operates outside of a specific game plan from opposing defenses, at least compared to how teams can attack 99% of the league.

"I think that's beyond game planning for," Bickerstaff said. "You go out and try to make his job as difficult as you possibly can. … Easier said than done. But you want to try to frustrate him by not giving him his first option. You want to make him have to send his team to the second, third and fourth option and see how good they are at that.

"From an individual, grand scheme, it's hard to game plan for greatness."

In the Lakers' win over the Cavs on Saturday night, James finished with 22 points, six rebounds, six assists and came away with many of the crucial plays down the stretch. He shot just 1-for-9 from 3-point range, which kept the damage at bay. But for the Cavs, James' passing was the bigger danger.

"He can make passes that 99.9% of the league can't make," Bickerstaff said. "I mean there's just not many things that he can't do. And not only does it stress you individually, but it stresses you as a defense as well."

Plenty around the league are still stressed that James is still doing what he's doing. But there's also a level of respect for it.

"I mean, everybody knows LeBron's the greatest player to ever play," said rookie guard Craig Porter Jr. "He's not just the best scorer, but he's the best passer and he just knows how to get his team open without even having to score the ball. … It just makes him one of the hardest players to guard and that's why he is who he is."

Ryan Lewis can be reached at rlewis@thebeaconjournal.com. Follow him on Twitter at @ByRyanLewis.

This article originally appeared on Akron Beacon Journal: Cavaliers discuss difficulties of guarding Lakers star LeBron James