Six games into the season, Denver Broncos quarterback Peyton Manning has thrown for 22 touchdowns and only 2 interceptions. If he continues at or near his present pace, he will generate the best statistical season of his career and one of the best by any quarterback ever, while at the age of 37. How long can he sustain this level of performance?
Sometimes, sports commentators let their sentiment run wild when it comes to long-lived and well-liked players like Manning or the Yankees' Derek Jeter and make statements to the effect that they can continue as long as they have desire. A less enthusiastic consideration from sports and life suggests otherwise. Time and age inevitably diminish athletic performance. Yale economist, Ray Fair, supplies extensive data on running and field event performances by age along with swimming and even chess. Masters running records indicate that by age 50 runners, whether in the 100 meters or mile, drop off by about 10 percent relative to world records. Of course, the incentives driving these records are not nearly as substantial as the open records and may not attract the most talented performers. During the height of PED use, particularly in baseball, 40 became the new 28, but even the modest enforcement policies of MLB have curtailed the drug-enhanced career lengths.
How long can Manning keep it up? After all, it's the skill in Manning's head and arm more so than his ability to run 100 meters that makes him great. Evidence collected specifically for NFL quarterbacks by Advanced NFL Stats offers clues. QBs over 35 tend to drop off with another precipitous drop after 37. These data indicate that the drop-off does not happen gradually. Instead, it’s usually quite sudden. As their analysis points out, however, the sudden drop-off could be an artifact of the data. All QBs experience up and downs in their careers, only to bounce back toward the mean in subsequent years. With a QB in his late 30s, the down year frequently leads to retirement and may accompany an injury, which imposes a selection bias on the data. Another selection issue with the data is that most (starting) quarterbacks who continue playing into their late 30s are among the league’s best, which makes for a small sample.