In [[baseball]], a pitcher has an infinite Earned Run Average (ERA) when he allows earned runs without obtaining any "outs" by the opposing team, because the ERA is a pitcher's average earned runs allowed per nine innings pitched (i.e., 27 outs obtained). In 2019, Nationals relief pitcher Trevor Rosenthal had an infinite ERA until he finally obtained an out.<ref>https://www.freep.com/story/sports/mlb/2019/04/11/trevor-rosenthal-nationals-reliever-infinity/3433399002/</ref> | In [[baseball]], a pitcher has an infinite Earned Run Average (ERA) when he allows earned runs without obtaining any "outs" by the opposing team, because the ERA is a pitcher's average earned runs allowed per nine innings pitched (i.e., 27 outs obtained). In 2019, Nationals relief pitcher Trevor Rosenthal had an infinite ERA until he finally obtained an out.<ref>https://www.freep.com/story/sports/mlb/2019/04/11/trevor-rosenthal-nationals-reliever-infinity/3433399002/</ref> |