Recently, someone posed the following question to me, “have the physical builds of MLB players changed over time?” I went to the Lahman Database to find the answer, breaking down the results by players’ most common position and the decade in which they debuted.

Player height has generally increased over time, though this most likely tracks the overall trend of the U.S. population.

Is weight more interesting? Absolutely. Expectedly, average weights have gone up over time. However, at least one local pattern appears to exist. Average player weights are going down for recent players.

Lastly, we can look at height-weight-ratio. The lower the value, the stockier the build. As expected, players are getting more stocky over time, but the trend has recently changed towards “slimmer” players. I also want to point to the steroid era, where there was clearly an acceleration in the stockiness of player builds.