New York Mets' Jenrry Mejia, MLB Starting Pitchers and Stamina

By Carlton Chin
Jenrry Mejia
Anthony Gruppuso – USA TODAY Sports

On Saturday, New York Mets pitcher Jenrry Mejia was cruising through five innings before giving up five earned runs in the sixth inning. This led baseball fans to say that Mejia can’t last more than five innings.

Early in the 2014 season, the Mets have limited Mejia to 100 or fewer pitches per start, which has generally resulted in five or six innings pitched. Mejia has been striking out more than one batter per inning pitched and has yielded almost five walks per nine innings pitched. If Mejia reduces his number of walks, he will become a more efficient pitcher and last longer into games.

And what about Mejia’s stamina and performance as he tires? Mejia has just five starts in 2014 so far; in his young career, he has had 16 starts. Mejia’s splits for his 16 starts do indeed show that he tires. Although the sample size is still very small, Mejia’s ERA in the sixth inning is a bloated 9.31 after Saturday’s game. It is interesting how numbers can sometimes be misleading. Before Saturday, Mejia’s ERA during the sixth inning was in the 4.50 range.

Still, this is higher than Mejia’s lifetime ERA of 3.90 (which was about 3.60 before Saturday). How do other major league starting pitchers fare in relation to innings pitched?

In today’s era, where relievers are used abundantly, a quick sampling shows that modern starting pitchers’ splits are fairly stable in terms of ERA as it relates to the actual innings pitched. Most starters’ splits show the best performance during the second inning, when they generally face the bottom half of the batting order. In each of the other innings through the seventh, ERA performance is fairly stable on average.

As the young 24-year-old Mejia matures, he will increase his arm strength and stamina. During Mejia’s time in the minor leagues, he was used as both a reliever and as a starter. This is one of the reasons why he needs time to build the stamina needed to be a major league starting pitcher.

Carlton Chin is a quant researcher and sports analysis contributor at Rant Sports. Please follow him on Twitter @QuantFacts, “Like” him on Facebook, or add him to your Google network.

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