In 2018, Jacob deGrom of the New York Mets had the lowest earned-run average (ERA is the mean number of runs yielded per nine innings pitched) of any starting pitcher in the National League, with an ERA of 1.70. Also in 2018, Blake Snell of the Tampa Bay Rays had the lowest ERA of any starting pitcher in the American League with an ERA of 1.89. In the National League, the mean ERA in 2018 was 3.611 and the standard deviation was 0.772. In the American League, the mean ERA in 2018 was 3.744 and the standard deviation was 0.893. Which player had the better year relative to his peers? Why?