Doctoring The Numbers: Starting Them Young, Part Two by Rany Jazayerli

Yesterday’s column made the claim that small differences in age among high school hitters can have a dramatic impact on their return as draft picks. Today, I intend to prove that claim. Rather than simply looking at the youngest and oldest players in each draft year, I’ve taken all 846 players in the draft study and separated them by age into five roughly equal bins: Very Young, Young, Average, Old, and Very Old. I then calculated the combined expected value of the players in each bin based on where they were drafted and the combined Discounted WARP that they actually generated. (If you want the technical details: “Very Young” players were less than 17 years, 296 days old on draft day; “Young” players were between 17 years, 296 days and 18 years, 38 days; “Average” players were between 18 years, 38 days and 18 years, 120 days; “Old” players were between 18 years, 120 days and 18 years, 200 days; “Very Old” p...