Major League Baseball (MLB) franchises expend an abundance of resources on scouting in preparation for the June Amateur Draft. In addition to the classic "tools" assessed, another factor considered is age: younger players may get selected over older players of equal ability because of anticipated development, whereas college players may get selected over high school players due to a shortened latency before reaching the majors. Additionally, Little League rules in effect until 2006 operated on an August 1-July 31 year, meaning that, in their youth, players born on August 1 were the eldest relative to their cohort. We examine the performance of players selected in the June Draft from 1987-2011. We find that for all draftees, more relatively old players are selected in the Draft. Conversely, for high school (HS) draftees, both relative age and absolute age have a significant negative relationship with the odds of reaching the major leagues. Given that a HS draftee reaches the majors, there is no difference in professional performance based on age or relative age, measured by games played, wins above replacement (WAR) and on-base plus slugging percentage (OPS). For college draftees the results are less clear. We find that age, but not relative age, has a significant negative relationship with the odds of reaching MLB. Given that a college draftee reaches the majors, there is no difference in professional performance based on age or relative age. Had the draft market operated efficiently, neither relative age nor age on draft day would have captured additional variation in performance after controlling for draft position and other factors. We conclude that teams have undervalued both absolutely, and relatively, younger high school players in the draft and have undervalued absolutely young and relatively old college draftees.
Sims, Justin, "Hurdle Models and Age Effects in the Major League Baseball Draft" (2014). Mathematics, Statistics, and Computer Science Honors Projects. 35.
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