NFL quarterback Tom Brady’s retirement and NBA basketball player LeBron James breaking Kareem Abdul-Jabbar’s longstanding scoring record have sparked renewed discussions and analyses of the G.O.A.T. (Greatest of All Time). It’s hard to turn on a sports station without avoiding such discussions. The problem is not only in defining what’s meant by “G.O.A.T.” but adjusting for factors that over time influence performance and playing statistics.

This is where economics helps. There are entire subdisciplines within economics dedicated to understanding the influence and power of rules and how they affect behaviour and performance over time. Moreover, economists are constantly adjusting data from nominal values to “real” values to account for the effects of inflation over time, so we’re well-versed in thinking about how to make adjustments to reflect changes over time.

Let’s start with the discussion of Tom Brady as the G.O.A.T. in professional football and for comparative purposes, let’s stack Brady against three other highly successful quarterbacks: Terry Bradshaw of the Pittsburgh Steelers, Joe Montana of the San Francisco 49ers (and later the Kansas City Chiefs) and Bart Starr of the Green Bay Packers.

Starr played from 1956 to 1971 and won three consecutive league championships and the first two Super Bowls. In 16 professional seasons, he won five championships, resulting in a championship win ratio of 31.3 per cent. Terry Bradshaw played 14 seasons from 1970 to 1983 and won four Super Bowls, resulting in a win ratio of 28.6 per cent. Montana played 16 seasons from 1979 to 1994, winning four Super Bowls for a win ratio of 25.0 per cent. Brady won seven Super Bowls over 23 seasons, resulting in a win ratio of 30.4 per cent, slightly less than Starr and just ahead of Bradshaw.

This is not to diminish Brady’s record of championships but rather to emphasize that to some extent his success winning championships is a result of a longer career. As medicine and sports science more generally have advanced, the length of athletes’ careers have been extended so analyses need to be careful about conflating longevity and performance, particularly with respect to career statistics such as passing, touchdowns, etc.

Consider, for example, what happens to career passing yards statistics when adjusted for the number of seasons played. As of the end of the 2022 season, Brady led with 89,214 followed by Drew Brees (80,358), Peyton Manning (71,940), Brett Favre (71,838) and Ben Roethlisberger (64,088). However, if we adjust career passing yards by the number of seasons played, Brady falls to third behind Brees and Manning. Again, there’s a risk of conflating longevity with performance.

In addition, the length of the regular season has changed over time. In 1978, the number of games increased from 14 to 16, and just recently in 2021, to 17. Put differently, the number of games played per season by quarterbacks such as Starr and Bradshaw is lower than those who followed and needs to be accounted for when considering career statistics.

But perhaps most importantly, the rules in the NFL have been changed to better protect the quarterback and promote a more offensively-oriented game. InsideHook’s Sean Cunningham (with the assistance of former NFL quarterback Tim Hasselbeck) assessed some of the more important rule changes that favour quarterbacks. In 1995, for instance, the NFL changed the rule so that defensive players could not unnecessarily or violently throw quarterbacks to the ground or land on them while tackling. In 2002, the NFL made it a penalty, and indeed a severe one, to hit a quarterback helmet-to-helmet. In 2006, the NFL prohibited defensive players from hitting quarterbacks low. These are just some rule changes that protect quarterbacks, which make it easier to perform and extend longevity.

Put simply, a host of rule changes coupled with medical and health advances have enabled players, particularly quarterbacks to extend their careers. When debating the G.O.A.T. these changes must at least be included in the discussions.

Rule changes should also feature prominently in any discussion about Lebron James surpassing Kareem Abdul-Jabbar’s NBA scoring record. Consider, for example, that when Kareem played, the NBA required players to attend college to be draft eligible, which means he spent four years in college compared to James who was drafted out of high school because the NBA changed the rule.

A recent analysis by Sporting News columnist Kyle Irving suggests that had Kareem not been required to play college ball before going professional, he could have reached 48,759 points, which he concludes “would almost certainly never be broken.” Kareem’s actual scoring record was 38,387, which James surpassed in February.

Another rules-based change that clearly influenced performance and specifically scoring is when the NBA introduced the three-point shot in 1979, in the middle of Kareem’s career. Prior to 1979, long-distance shooting was not as valued as inside play, which Kareem dominated. Interestingly, Kareem only made one three-point shot in his professional career whereas James, as of the beginning of February 2023, had made 2,237 three-pointers in regular season play, which represents a material points advantage.

Again, this is not to discount James’ accomplishments but rather to recognize how rule changes over time influence performance and any comprehensive debate about the G.O.A.T. in any sport.