Reverse Platoon Splits – Before and After

Tom Tango asked someone to see what players with at least a 30-point wOBA reverse platoon split in their first 2500 plate appearances did for the rest of their careers, and Sean Foreman kindly provided split data from his database.

So I hacked together a Perl script to read his data and analyze it. The script lets you tweak filters, setting a minimum reverse split over some minimum number of plate appearances versus both left and right handed pitchers. Taking Tango’s suggested criteria, I found just 7 matching players, with an aggregate 40 point negative wOBA split:

                             Before                                   After
                        vs LHP     vs RHP                      vs LHP       vs RHP
Player     years     wOBA    PA  wOBA   PA  Split   years    wOBA   PA    wOBA   PA  Split
glanvdo01 1996-2000 0.313   710 0.346  2005 0.033 2001-2004 0.321   431 0.280  1136 -0.041
batisto01 1996-2002 0.316   872 0.351  2454 0.035 2003-2007 0.291   462 0.310  1171  0.019
bergewa01 1930-1935 0.365   538 0.407  2101 0.041 1936-1940 0.385   289 0.370  1335 -0.015
jonesad01 2006-2012 0.316   870 0.358  2246 0.043 2013-2018 0.334  1021 0.344  2851  0.010
samueju01 1983-1987 0.320   840 0.351  2036 0.030 1988-1998 0.344  1556 0.310  2232 -0.034
leeca01   1999-2003 0.329   642 0.367  2347 0.038 2004-2012 0.373  1396 0.357  4402 -0.015
jacksra01 1950-1956 0.311   599 0.359  2174 0.048 1957-1959 0.277    74 0.276   326 -0.002
Total               0.322  5071 0.362 15363 0.040           0.345  5229 0.336 13453 -0.009

Tango expected the group would be neutral, and in aggregate they showed a 9-point “normal” split in wOBA. Only two of the 7 still showed a reverse platoon split, and in both cases it was much narrower than their start of career split.

But just 7 batters making his cutoff seems a little small of a sample size. So I reran, this time allowing batters with at least a 20 point wOBA reverse split, and now I get 25 players whose aggregate split is 30 points:

                             Before                                   After
                        vs LHP     vs RHP                      vs LHP       vs RHP
Player     years     wOBA    PA  wOBA   PA  Split   years    wOBA   PA    wOBA   PA  Split
glanvdo01 1996-2000 0.313   710 0.346  2005 0.033 2001-2004 0.321   431 0.280  1136 -0.041
casege01  1937-1945 0.313   705 0.339  2216 0.027 1946-1947 0.298   129 0.270   348 -0.028
heganji01 1941-1952 0.286  1076 0.306  2123 0.020 1953-1960 0.291   876 0.296  1146  0.005
batisto01 1996-2002 0.316   872 0.351  2454 0.035 2003-2007 0.291   462 0.310  1171  0.019
spencda01 1952-1959 0.304   662 0.326  2088 0.022 1960-1963 0.366   449 0.337   913 -0.029
perezto01 1964-1970 0.352  1071 0.377  2261 0.026 1971-1986 0.388  2358 0.334  5166 -0.054
bressed01 1956-1964 0.316   827 0.342  2378 0.026 1965-1967 0.308   294 0.294   574 -0.015
mondera01 1993-1998 0.349   719 0.376  2366 0.027 1999-2005 0.383   740 0.338  2544 -0.045
wilsopr01 1998-2003 0.343   791 0.367  2242 0.023 2004-2007 0.375   367 0.320  1036 -0.054
disarga01 1990-1997 0.275   846 0.299  2251 0.024 1998-2000 0.311   213 0.310   722 -0.001
jonesad01 2006-2012 0.316   870 0.358  2246 0.043 2013-2018 0.334  1021 0.344  2851  0.010
zimmedo01 1954-1962 0.284   566 0.305  2053 0.021 1963-1965 0.294   300 0.316   674  0.022
hemslro01 1928-1939 0.296   721 0.323  2068 0.027 1940-1947 0.322   434 0.288  1108 -0.034
cimolgi01 1956-1963 0.307  1008 0.327  2258 0.020 1964-1965 0.141    53 0.287    23  0.146
ugglada01 2006-2009 0.340   645 0.370  2053 0.030 2010-2015 0.332   760 0.333  2051  0.001
suzukku01 2007-2012 0.292   780 0.321  2171 0.029 2013-2018 0.343   640 0.309  1728 -0.034
samueju01 1983-1987 0.320   840 0.351  2036 0.030 1988-1998 0.344  1556 0.310  2232 -0.034
fiskca01  1969-1977 0.358   778 0.380  2047 0.021 1978-1993 0.349  2292 0.341  4736 -0.008
jacksra01 1950-1956 0.311   599 0.359  2174 0.048 1957-1959 0.277    74 0.276   326 -0.002
bergewa01 1930-1935 0.365   538 0.407  2101 0.041 1936-1940 0.385   289 0.370  1335 -0.015
ludwiry01 2002-2011 0.328   947 0.356  2027 0.027 2012-2014 0.376   267 0.323   745 -0.053
boonebo01 1972-1978 0.301   820 0.325  2090 0.024 1979-1990 0.293  1629 0.295  3609  0.001
hollima01 2004-2008 0.388   660 0.415  2308 0.027 2009-2018 0.391  1309 0.373  3704 -0.018
hornebo01 1978-1983 0.365   638 0.389  2078 0.024 1984-1988 0.392   479 0.347  1018 -0.045
leeca01   1999-2003 0.329   642 0.367  2347 0.038 2004-2012 0.373  1396 0.357  4402 -0.015
Total               0.321 19331 0.352 54441 0.030           0.347 18818 0.331 45298 -0.017

Now we finally find a player, Don Zimmer (yes, the former Red Sox manager and Yankees coach!) who showed a greater reverse split over the rest of his career than the start, but again just barely, increasing to 22 points from 21. Just 6 other players showed any reverse split at all over the rest of their careers, and two just by a single wOBA point.

When I set the filter back at 30 wOBA points, but require fewer PA (250 against LHP, and 1000 against RHP),  I find a total of 57 players, with this aggregate:

Total               0.308 25543 0.348 67831 0.040           0.349 37399 0.331 93823 -0.018

Interestingly, this group in aggregate shows an 18-point normal platoon split over the rest of their careers, after a 40 point reverse split from the start of their careers.

So overall, it seems that even players who show a pronounced reverse platoon split tend to show a more normal platoon split over the rest of their careers.

If you want to tinker with different filters, you can download the raw data Sean Foreman made available, and pass it to my Perl script with different arguments.

About Geoff

Dad, hacker, fantasy sports entrepreneur.
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