Thirty is the new forty. At least it seems that way for the NBA players who entered the league straight from high school and put their bodies through the rigors of an 82-game schedule while their counterparts were playing less than half as many games in college. By the time they hit 30, the additional wear and tear manifests in a notable dropoff from their peak performance.

Most players hit their physical peak at age 27. The decline by 30 is noticeably steeper for the high schoolers. A look at the 30-year-old seasons of prominent members of that group shows a dropoff of 13 percent to 60 percent from their top Player Efficiency Rating.

LeBron James is the latest in the 10-year wave of preps-to-pros players from 1995 to 2005 to turn 30, and right on cue he’s showing advanced signs of age. Two days after his 30th birthday, James was given a two-week respite by the Cleveland Cavaliers to heal his ailing knee and back. He could wind up missing as many games over the next two weeks as he has in any full season during his career. Meanwhile, he is posting a PER of 25, 21 percent below his peak of 31.7 at age 24.

The charts below, with data culled from Basketball-reference.com, compares the peak PER to the PER at age 30 for prominent high school-to-NBA players. (The website goes by the player’s age at Feb. 1 of the season). The next chart shows the PER at age 30 for players who went to college and are deemed statistically similar by basketball-reference.com.

Just for comparison’s sake, there’s a list of age 30 dropoffs for some all-time great players who played in college before heading to the NBA. You’ll notice their dropoff at age 30 is usually around 5 percent.

A couple of notes: Tyson Chandler was a rare player who actually posted his best PER after he turned 30. (It’s worth remembering that he never played more than 2,000 minutes in a season until his fourth year in the league.) And Michael Jordan didn’t play a full season at 30; that was in the midst of his first retirement. For comparison, we used his numbers from 1992-93, his 29-year-old season. His 30th birthday was Feb. 17, 1993, or 16 days after the basketball-reference.com cutoff.