This deep-dive analysis demonstrated that MLB umpires make certain incorrect calls at least 20 percent of the time, or one in every five calls. Research results revealed clear two-strike bias and pronounced strike zone blind spots. Less-experienced younger umpires in their prime routinely outperformed veterans, and umpires selected in recent World Series were not the best performers. Results showed a declining but still unacceptably high BCR score, but on a positive note, only a marginal inter-inning call inconsistency.
The most likely mistakes are made at the top of the strike zone. And older umpires really are worse:
Based on the research, professional umpires, similar to professional baseball players, have a standard peak. The study revealed that home plate umpires who made the Top 10 MLB performance list (2008-2018) had an average of 2.7 years of experience, and averaged 33 years of age with a BCR of 8.94 percent. None of these top performers had more than five years of experience or were older than 37…
In contrast to the overall top performers, research uncovered that umpires on the Bottom 10 MLB performance list (2008-2018) had an average experience level of 20.6 years, were 56.1 years of age, and had an average BCR of 13.96 percent. This group’s error rate was a staggering 56 percent higher than the top 10 MLB performers. Umpire Jerry Layne, with 29 years on the job and at age 61, sported the highest BCR, 14.18 percent. This performance research clearly indicates that more experience and age does not necessarily produce the best umpires.
Here is the full story, written by Mark T. Williams, who also did the data work, via the excellent John Chamberlain.