Baseball America's Matt Eddy posted a compelling piece on Tuesday, outlining how BA's research over the last few seasons in the minor leagues has allowed them to take the next step in quantifying park factors at levels other than the Major Leagues. When we've broached this topic in the past, we've stuck to generalities exactly like Eddy expresses: the Florida State League is a pitcher's league. Thankfully, those of us who were interested in a finer understanding of minor league park factors now have a resource.
I'll leave it to you to read their whole breakdown of the method, but here's the meaty part for me:
"In statistical analysis, it's important to determine the correlation between two sets of numbers—in other words, whether one number is meaningful in predicting another. A fancy term for this is the "coefficient of determination," also called R-squared, which is represented as a number between zero and one, with one being perfectly predictive. An R-squared of .50 indicates a good correlation, so the .89 R-squared between hits and runs is almost startlingly strong.
Moderate to strong correlations exist between hits and home runs (.41) and home runs and runs (.48). No other comparisons yielded a positive correlation, with walks and strikeouts (.00) and home runs and strikeouts (.01) showing particularly weak correlations."
BA's research took them back to 2010, which of course means their data covers the past three seasons of minor league baseball. Here is how the affiliates for the Twins' minor league ballparks shook down.
Rochester Red Wings - AAA International League
League Runs Per Game: 8.74 (9th out of 10)
League Hits Per Game: 17.43 (4th)
League Home Runs Per Game: 1.67 (3rd)
Team Runs Per Game: 9.14 (4th out of 14)
Team Hits Per Game: 17.94 (3rd)
Park Factor: 1.115 (3rd)
Summary: In a league where pitching is actually pretty strong, hitting in Rochester was a relatively fruitful exercise. This isn't necessarily good news considering the lack of incredible hitting performances we've seen from the Red Wings in recent years (having to adjust their performances by, rounding up, 11%), although that's just as much the organization's fault as it is the park's or the league's. But conversely, it's slightly more encouraging for Rochester's pitchers.
New Britain Rock Cats - AA Eastern League
League Runs Per Game: 8.92 (6th out of 10)
League Hits Per Game: 17.26 (6th)
League Home Runs Per Game: 1.52 (5th)
Team Runs Per Game: 9.43 (4th out of 12)
Team Hits Per Game: 17.84 (3rd)
Park Factor: 0.992 (7th)
Summary:The Eastern League is actually pretty balanced, and in New Britain things were pretty much down the middle. The interesting part is that team runs and hits were actually leaning towards the top while, in the big picture, the park actually leans very slightly for the pitchers. This is partially due to the fact that home run rates were 9th in the league.
Fort Myers Miracle - Advanced A Florida State League
League Runs Per Game: 8.58 (10th out of 10)
League Hits Per Game: 17.03 (9th)
League Home Runs Per Game: 1.13 (10th)
Team Runs Per Game: 8.56 (6th out of 12)
Team Hits Per Game: 17.28 (4th)
Park Factor: 0.970 (9th)
Summary: The good news is that what we always said about the Florida State League has held true, at least when we look at the last three years - it's a very pitcher-friendly league. Jupiter, for example, allows just 0.73 home runs per game, and looking at Brevard County their Park Factor is 0.908. That's crazy. In Fort Myers is a pretty significant pitcher's park in a pitcher's league. So, that's fun.
Beloit Snappers - Low Class A Midwest League
League Runs Per Game: 9.13 (5th out of 10)
League Hits Per Game: 16.96 (10th)
Home Runs Per Game: 1.24 (9th)
Team Runs Per Game: 9.16 (8th out of 16)
Team Hits Per Game: 16.78 (9th)
Park Factor: 0.969 (14th)
Summary: When we examine the fantastic pitching performances of some of our younger pitchers, understanding these park effects should be taken into account. While factors like strikeout rates (which are strong for players like Berrios, Bard, Melotakis and Chargois) don't have a high correlation with park effects, it is worth noting when we look at the number of hits, home runs, and runs they allow while in the lower echelons of the Minnesota farm system. Of course this is useless going forward as Beloit is no longer a member of the organization's affiliate teams.