The curious case of Glendon Rusch

Glendon Rusch had a fairly unremarkable career by most standards. After struggling with the Royals early on, the left-hander had two solid years as a back-end starter for the Mets in 2000 and 2001. He then had somewhat rocky stints in Milwaukee, Chicago, San Diego, and Colorado, before retiring with a 67-99 record and a 5.04 ERA.

While Rusch’s numbers don’t jump off the page, buried among them is actually one of baseball’s more interesting statistical anomalies. Rusch’s career ERA was 75 points higher than his 4.29 career FIP, which measures only the factors that a pitcher directly controls—strikeouts, walks, and home runs—and is considered a better indicator of future performance than ERA.…