Astromets Mind: Minor League Guts

Minor League Guts

Play-by-play data for this page was obtained using the pitchRx package on RStudio (thanks to Carson Sievert for the package), with data from 2011-2015 scraped straight from the MLB site. My goal here was to reproduce the Fangraphs guts page for the minor leagues.

Linear Weights






            Fangraphs scales their weights so the runSB value will be 0.200, but I had to scale my weights to the Fangraphs league average, so there are minor differences in the final results. The ‘Delta Mean’ column represents the average absolute difference between the Fangraphs reported wOBA values and those calculated with these weights (I only considered position players for the Delta Mean calculation). Color scaled to league average wOBA.

Minor League Park Factors






            These are single-year park factors calculated using the method Fangraphs claims to use (link). The patterns generally agree with the park factors reported here, but my numbers appear to be closer to 100. The league totals aren’t always a perfect match with Baseball-Reference reported totals, but the differences are very minor (less than 0.05% of the total PA count per league each season).
The games column represents the number of games at home. Note that I did not consider any possible in-season home-stadium changes for these calculations. Also, the numbers can get a bit more extreme in the short season leagues, but remember how small the samples are, especially if you’re looking at handedness park factors (see below) at the short season level (although you probably don’t need to waste time looking at short season stats anyway). Color scaled to the teams runs park factor.

Minor League Handedness Park Factors







            I applied the same method as above to the handedness park factors, but I don’t have any source to compare the data to, so let me know if something seems suspect. Color scaled to the teams HR park factor.
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