Hitter/Pitcher-Friendly Leagues

I had a random thought about the differences between minor leagues in terms of being hitter-friendly or pitcher-friendly. I’ve often read qualifications of individual performances, for example, “he’s hitting well, especially since that’s a pitchers’ league,” or “his ERA is not bad, considering that he’s in a hitter-friendly league.” So I decided to go to the stats. I chose to compute the averages of the last five complete regular seasons, 2013-2017. But which stats to use? Runs per game? ERA? Batting average? I decided to compile OPS and ERA as the measurements for hitting and pitching, respectively. I knew that the two would be highly correlated, and that was indeed the case. I really didn’t see anything interesting by considering both stats together, so I simply sorted the leagues by OPS. The data appears in the table below.


I was surprised to see the huge difference between the top and the bottom: 126 points of OPS, 1.59 earned runs! The next surprise was that the leagues don’t cluster much by level. The Rookie leagues are all over the map.

I had a few ideas to explain the differences, then the Commish suggested a few others. Here’s a list of possible explanations.

  • Elevation. The Pioneer and Pacific Coast Leagues parks are generally at higher elevations, which helps the hitters.
  • Big Spring Training Parks. The Florida State League teams play in the Spring Training parks, which are big. The same probably goes for the Gulf Coast League, even though those are back fields.
  • Wood Bats. Hitters in the Short-Season A leagues may be at a disadvantage, because some of the hitters are using wood bats regularly for the first time.
  • Windy Florida. Maybe windy conditions are tough on the hitters in the Florida State League and GCL.

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