I’d rather trade a player a year too early than a year too late. -- Branch Rickey

An 82-game NBA season takes a brutal toll on the bodies of its players. For six months, they’re sprinting up and down 94-foot courts, beating on each other, flying high into the air and crashing to the ground. Almost every first-year player eventually hits the “rookie wall”, overwhelmed by the sheer toll of playing four games in five nights and traveling to four cities stretched across thousands of miles in seven days.

An athlete is like a sports car: the more miles on their body, the more wear and tear. The average length of an NBA career is only 4.8 seasons; a 10-year player has survived the league being turned over twice. Almost no one makes it to 15 years; the ones who do are usually Hall of Famers or 6’11 centers, mostly because there aren’t enough athletes that size in the world to fill NBA rosters.

Just as in baseball, there’s a clear aging curve when it comes to basketball players in their 30’s, with few remaining effective into their second decade in the league. Yet, while name-brand veterans should be viewed skeptically, many coaches instead bend over backwards to give guys with so much NBA experience playing time, often to the detriment of their own teams. Knowing what to do on a court is great, but if you can’t get there fast enough, it doesn’t really make a difference.

Last summer, while working on a piece projecting the top 100 players in the NBA in the year 2016, I looked at where the top 112 players in 2011 were in 2006. The results were surprising: over half (58) were under the age of 22. In contrast, there were only 17 over the age of 27. As basketball players move from their late 20’s to their early 30’s, the threat of them falling off a cliff grows with every passing season.

The threat is particularly great with undersized players. If a guy is 2-3 inches shorter than the players he matches up with, he generally needs to be more athletic, making up for a lack of stature with the ability to get off the ground and move his feet faster. As a result, when the wheels fall off, those players have less to fall back on.

In comparison, guys 2-3 inches taller than the players they match up can often slide down the position spectrum and prolong their careers. Kevin Garnett and Tim Duncan, both 7’0, have been able to successfully transition from the 4 to the 5. Rashard Lewis, at 6’10, has found a second life in Miami playing as a stretch 4/5 instead of a 3/4 wing. Jason Kidd, at 6’4, now plays primarily at shooting guard for the Knicks after an 19-year career as a 1. A 6’0 PG or a 6’9 PF doesn’t have the same options.

To make it worse, players hitting the wall are often at the tail end of long-term contracts signed when they were still in their prime. For example, the Wizards are paying Emeka Okafor $27 million over the next two years and I’m not sure I’d want him on my team for free. At 6’10 250, he’s an undersized center with marginal offensive skills who relies on athleticism to get by. Every year, he becomes less valuable as his gets slower and slower off the ground. Through the first 12 games of the season, he’s shooting 40% from the field. That’s a miserable number for a guard, much less a big man.

The effect of declining athleticism on defense is obvious, but it can also eat away at a player’s offensive value too. A telling moment for Elton Brand, another aging and undersized big man, came in the Mavs loss to the Lakers last week, when the 33-year old picked up a three-second violation after an offensive rebound. With Dwight Howard and Pau Gasol “putting him in jail,” all he could do was pump fake and hope for the best, as he had no chance of scoring over their outstretched arms. On the season, Brand is shooting 34.5% from the floor.

Of course, a month is still a fairly small sample size. There’s always the chance that a guy like Brand or Okafor recovers from their career-low statistics. However, sticking with a player like that has a low upside and a very high downside. In a situation like the Dallas front-court, where Rick Carlisle has stubbornly stuck with Brand and Troy Murphy while keeping more productive younger players chained to the bench, the decision-making process is so baffling that something else must be at play.

Carlisle, like many NBA coaches, played in the league, but he was far from a star. He lasted a little over four seasons with the Celtics, Knicks and Nets in the mid-1980’s. But while he wasn’t a great NBA player, he was still a great basketball player, one of the top 400 in the world. As a result, he almost certainly had a healthy ego, which would have made his inability to get consistent playing time galling. Every player monitors the production of the guys getting minutes ahead of him, making it easy for a journeyman like Carlisle to resent younger players being given opportunities based on their upside, not production.

In the case of Avery Johnson, an undrafted free agent who stuck in the NBA for over 15 years, it would only be natural for “The Little General” to see himself in older veterans who get by on guile and savvy, not athleticism. In his time in Dallas, he rarely passed up the chance to play veterans at the expense of younger players. In 2006, he chained Marquise Daniels to the bench in order to start Adrian Griffin. In 2007, it was Devean George. In 2008, he assembled a bench with prominent roles for Jerry Stackhouse (33), Eddie Jones (34) and Juwan Howard (34).

In Brooklyn, he’s taken that philosophy to its logical conclusion. While MarShon Brooks (24) has the second highest PER on the team, he’s losing minutes to Stackhouse (38) and Keith Bogans (32), neither of whom have a PER near the league average of 15, or had a consistent role in an NBA rotation last season. Stackhouse and Bogans may be more adept at doing the little things on the court that help a team win games, but the big things (i.e. being a statistically productive basketball player) are kind of important too.

Ten-year NBA veterans should have the respect basketball fans for what they have accomplished in their careers, but that doesn’t mean they no longer have to prove they are worthy of minutes. In fact, it’s the exact opposite. With the amount of basketball talent in the world at an all-time high, the burden of proof should be on the veteran to show he’s capable of overcoming the aging curve. Father Time, as Charles Barkley often says, is undefeated.