Not For Long. The phrase has grown into a mantra for the NFL, a reminder of how quickly a career can end.That was not exactly the intention of Houston Oilers coach Jerry Glanville, who once coined the phrase while yelling at an official: “This is N-F-L, which stands for ‘not for long’ when you make them f—ing calls.”Still, it seems to suit playing careers accurately. But how accurately?Inside: At what age do NFL players peak? Plus every team’s most intriguing newcomer heading into training camp. Let’s go.This article is from The Athletic’s NFL newsletter. Sign up here to receive it directly in your inbox. It’s free to subscribe. Average NFL career length?Commentators usually describe the average length of an NFL career as being about 3 1/2 years, often citing this 2002 story in The New York Times.That article was based on 1987-1996 data from the NFLPA. It raised questions of exactly which players counted as having been on rosters — along with how much the numbers might have changed since then.Some partial answers might have arrived via a Roger Goodell conference call in 2011, when the commissioner said:“Frequently, it is said that the average career is about 3 1/2 years. In fact, if a player makes an opening-day roster, his career is very close to six years. If you are a first-round draft choice, the average career is close to nine years. That 3 1/2-year average … adds a lot of players who don’t make an NFL roster, and it brings down the average.”It’s fair to say that there’s no definitive answer on the “average” NFL career.So I dug a bit deeper. This chart shows the number of games played by each age group from 2000 through 2025, sorted by offensive position. This illustrates the ages when players actually saw the field most:It’s certainly a young man’s game, with the majority of impact coming between ages 23 and 27.The culprit? Speed and sustainability plays a role — these are massive humans colliding at full speed, after all — but what neither Goodell’s 2011 comment nor the NFLPA’s 1990s study could account for were the effects of the rookie wage scale.Introduced in a 2011 agreement between the union and league, the scale forces all draftees (typically between ages 21 and 23) into non-negotiable, four-year contracts usually below market value. It’s a big reason why the careers of so many of those charted players peaked around ages 24 and 25. Those ages include nearly all rookie-contract players, many of them at the midpoint of being affordable and having NFL playing experience.When are NFL players at their best, though? Let’s examine that now.Finding NFL primesThe idea of players “peaking” — being at the best of their abilities — is common across sports. Players know it. Coaches seek it. Fans understand it. But quantifying it? A definitive statistical measurement is tough to even imagine.