Grant Brisbee, The ERAs That Have Never Existed In Baseball History:
I'm a huge nerd, and I feel like it is my mission to discover the ERAs that haven't yet been achieved.
While plenty of pitchers have ended a season with a 0.00 ERA, no one has ever had an ERA of 0.01. Or 0.02. Or 0.03. Or 0.04 ...
The lowest ERA in history that is higher than zero is 0.38, achieved by Buck O'Brien in 1911 and Joba Chamberlain in 2007. Brisbee points out that Chamberlain holds the mark because his ERA was rounded up from 0.