During his 15th NBA season, Cleveland Cavaliers star LeBron James is performing at a level that echoes the prime that saw him win four MVPs.

As James nears his 33rd birthday later this month, his performance at that age stands up to any of his predecessors, including Michael Jordan's 1995-96 season that produced an MVP, a then-record 72 wins and a championship. (Because James entered the NBA directly out of high school, NBA experience isn't the best way to compare how he's aging to his peers. After all, Jordan's 15th year was actually his final one in the NBA at age 40.)

Given his age and the heavy minutes James has played since coming to the NBA at age 18, including extended playoff runs with trips to the NBA Finals each of the past seven years, his ability to stave off a decline in play has been improbable. Has James managed to break the aging curve that governs most NBA players?

James has been declining -- in the regular season

Before this season, a look at James' all-in-one metrics during the regular season would have looked like a fairly typical NBA aging curve, albeit shifted with a far higher peak than virtually any player in league history has enjoyed. Here's a plot of his ratings by player win percentage, the per-minute version of my wins above replacement player (WARP) metric akin to PER.

Kevin Pelton

After a relatively poor rookie season -- only by his high standards could winning Rookie of the Year and playing at an above-average level in the NBA as a teenager be considered relatively poor -- James quickly leaped into superstardom and improved gradually from there. His four best seasons came from ages 24 through 28, a stretch interrupted only by a down performance from James in 2010-11, his first year with the Miami Heat. The best-fit curve suggests James peaking just before age 27, the expected time for an NBA player, and declining gently from there.

The aging curve gets a bit more complicated when we consider James' playoff performance. Here's how that looks using the same chart:

Kevin Pelton

With the notable exception of 2009, when a limited Cleveland team lost in the Eastern Conference finals despite James delivering the best player win percentage in modern playoff history (since 1977-78, the first year individual turnovers were tracked), the curve now flattens out. James' past two postseasons have been about as good as any in his career outside of 2009. This is especially clear when we plot regular season and playoff performance together:

Kevin Pelton

There's strong evidence to suggest James mastered the art of coasting after rejoining the Cavaliers. As Brian Windhorst noted before the season using research by our former colleague Tom Haberstroh, James has consistently been better in the second half of the past four seasons -- a split that wasn't previously apparent.

This pacing is, of course, its own kind of concession to aging. Surely, if James felt he could still play at his playoff level over a full 82 games, he would have done it. Nonetheless, it suggests that James' age-related decline is more complex than charting his regular-season performance made it seem.

How James has reversed aging this season

Even an aging curve with gentle decline like James has experienced so far during the regular season will typically get steeper (downward) as a player heads toward his mid-30s. That makes it all the more surprising that instead of declining sharply, James has instead trended the other direction so far in 2017-18. His current .796 player win percentage, highest in the NBA, would be James' best mark since 2012-13 -- his last MVP season at age 28. Editor's Picks Pelton mail: Greatest defensive players of modern era

It's unclear whether James can keep up that performance. His efficient scoring thus far (James' .658 true shooting percentage would be the best of his career, and the second-best on record behind Stephen Curry's 2015-16 MVP season among players who used at least 30 percent of their team's plays, according to Basketball-Reference.com) has benefited immensely from career-best 41.7 percent 3-point shooting. Given James has shot better than 38 percent from downtown only once in his career, it's unlikely he'll continue to be so accurate from 3-point range.

At the same time, he's getting better shots now than perhaps ever before. According to Basketball-Reference.com, 43.7 percent of James' attempts have come within three feet, the second-highest rate of his career. Remarkably, despite the fact that a player's dunks per minute typically decline from the moment they enter the NBA, James made a career-high 145 dunks last season. (He's down from that pace this year, but his 5.3 layups per game would be a career-high, per Basketball-Reference.com.)

Additionally, James' rate of 2-point jumpers from beyond 16 feet is his second-lowest ever. So Second Spectrum's analysis shows that the quantified shot quality (qSQ) of James' shots -- the effective field-goal percentage (eFG) an average player would be expected to make based on the location of the shot and nearby defenders -- is the highest in the five years they've tracked this metric.

LeBron James' shot quality, since 2013-2014 Season qSQ eFG% 2013-14 51.2 61.0 2014-15 47.9 53.5 2015-16 51.7 55.1 2016-17 51.9 59.4 2017-18 52.7 63.0 Source: Second Spectrum

Remember, James is doing this without an All-Star point guard, since Cleveland traded Kyrie Irving and Isaiah Thomas has been unable to play yet because of a hip injury. Thomas could be back on the court this month, taking some of the defensive focus off James.

James also has defied aging in another interesting area this season. His 2.8 percent block rate would be the highest of his career by a wide margin (James posted a 2.4 percent block rate in 2008-09 and has been above 2.0 percent just two other seasons). Because of their relationship with athleticism, particularly for perimeter players, blocks -- like dunks -- tend to peak at the very start of a player's career. Indeed, James' block rate was at its highest from age 23-25. Last season was his third-lowest rate, less than half this year's.

LeBron's battle with Father Time

As the expression goes, Father Time is undefeated. But James is at least making him sweat.

To be clear, James is not quite the player he was at his peak because his defensive value -- blocks aside -- is not as high. And as he reaches his mid-30s, declining athleticism could finally become an issue for James, particularly if his improved 3-point shooting proves fluky.

The aging curve has always been more general guide than hard-and-fast rule. In the NBA, a player ages at his own pace, one determined by health, work ethic and countless other factors. James can't break it any more than Karl Malone did by winning his first MVP at age 33 and a second at age 35 or Kareem Abdul-Jabbar did by remaining a starter on a championship team well into his 40s.

Nonetheless, what James has accomplished this season is remarkable. Though age is the better predictor of a player's decline than years in the league or mileage, there is some evidence that a heavier load of minutes can accelerate the aging process. Nobody has faced a heavier load than James. Having already passed Jordan's career total, he recently jumped Shaquille O'Neal to move into 24th in career minutes played during the regular season. Only Tim Duncan has played more minutes than James in the playoffs.

There's some reason to believe the prime for NBA players has extended because of an increased focus on maintaining health and performance, as well as improved techniques and technology. Just as James is historic in the minutes he has played since a young age, so too is his dedication to playing at a high level. His business partner, Maverick Carter, told Bill Simmons last year that James spends $1.5 million a year on his body. That investment appears to be money well spent.