Episode Summary
Executive Summary: The episode revisits MLB’s 2015-2017 home run surge and centers Dr. Meredith Wills’s investigation showing the ball itself changed: thicker laces likely altered aerodynamics and grip, contributing to more homers and pitcher blisters. It then shifts to Justine Siegal’s trailblazing path as MLB’s first female coach and her work expanding girls’ access to baseball.
Main Topics: The 2015-2017 MLB home run surge (Priority: 5/5): The hosts reopen the question of why home runs spiked across baseball and why prior MLB investigations failed to find a clear cause. Dr. Meredith Wills’s baseball-forensics approach (Priority: 5/5): Wills explains how her astrophysics background and seam-by-seam deconstruction of baseballs helped her identify structural differences between pre- and post-2015 balls. Thicker laces as the likely smoking gun (Priority: 5/5): Her key finding was that newer baseballs had laces about 9% thicker, which changed ball bulge, feel, and possibly aerodynamic behavior. Pitcher blisters and grip-related effects (Priority: 4/5): The discussion links thicker laces and possibly wider seams to increased finger friction, blisters, and injuries among pitchers like Rich Hill and Aaron Sanchez. Reaction from MLB and alternate hypotheses (Priority: 4/5): The transcript notes MLB’s limited response and mentions other theories, including smoother leather, an off-center core, or roundness differences, though Wills argues validation is still needed. Justine Siegal and women in baseball (Priority: 5/5): The second half spotlights Siegal’s journey from being told to quit baseball to becoming a professional coach and founder of Baseball for All. Baseball culture, analytics, and what fans value (Priority: 3/5): The hosts and guests debate whether home runs or fielding excellence better represent baseball’s beauty, while acknowledging how modern offense shapes fan interest and revenue.
Key Arguments: MLB knew something changed in the baseballs, but the official investigation initially could not identify the mechanism. Wills’s analysis found the most distinctive change was thicker red laces on post-2015 balls, not necessarily higher seams. Thicker laces altered how the ball dried and deformed, producing seam bulging in older balls and a more spherical shape in newer ones. Pitchers can detect ball differences by touch, and even non-players in Wills’s demo could distinguish pre- and post-2015 balls by feel. The rise in pitcher blisters is consistent with a more abrasive grip surface caused by thicker laces and possibly wider seams. MLB and Rawlings may not have intentionally engineered the effect; it could have resulted from manufacturing or contract decisions without foreseeing gameplay consequences. Home runs are exciting but can reduce the role of defense; better all-around play, especially fielding, is also a major part of baseball’s appeal. Siegal argues that education, sports psychology, and persistence can help break barriers and make baseball more inclusive for girls and women.
Data Points: Home run surge period: 2015-2017 - The mystery being revisited centers on the spike in home runs during these seasons. Lace thickness change: 9% thicker - Wills’s key measurement comparing newer baseballs to pre-2015 balls. Baseballs bundled before/after commission change: Bud Selig signature = pre-2015; Rob Manfred signature = post-2015 - Used as a visual marker for identifying ball eras. Baseballs produced per week per worker: about 200 a week each - Wills references hand-lacing labor in Costa Rica. Pitcher blister spike: factor of five or factor of eight - A cited large increase in blisters in 2016, referenced as supporting evidence. Girls in national baseball tournament: about 400 girls - Siegal says the national girls tournament is growing and will feature roughly 400 participants. Growth rate of girls’ tournament: about 100 girls every year - Annual growth cited by Siegal for the Baseball for All program. Age when Siegal was told to quit: 13 - Her coach told her she should quit baseball because she was a girl. Start of coaching goal: 16 - Siegal says she decided to make coaching her goal at age 16.
Pivotal Quotes: "I found that the laces themselves are actually thicker by 9%." — Dr. Meredith Wills: Her central finding explaining the baseball change. "I would be very surprised if anybody intentionally went out and got laces that are 9% thicker." — Dr. Meredith Wills: Her view that the change was likely unintended rather than a deliberate performance tweak. "I just decided I would keep playing forever." — Justine Siegal: Siegal describing how she responded when told to quit baseball at age 13.
Implications: The episode suggests the home run spike may have been driven by subtle manufacturing changes with real performance and injury consequences. It also highlights how persistence and science can reshape baseball and expand who gets to play it.