March 29, 2001

The International League vs. The Pacific Coast League

Making the Case

by Clay Davenport

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Monday's article by Keith Scherer caused a few people to inquire about a particular statement, that the International League was clearly the top minor league. The statement was inspired by a chart in Baseball Prospectus 2001, in the introduction to the Davenport Translations.

Given the level of response to Scherer's use--correct use, in this case--of the material, I thought it would be useful to explain the conclusion a bit more deeply. The evidence is based on how players do who move from one league to another, using Equivalent Averages, adjusted for league and park, but without any adjustments for "difficulty."

Here's one piece. Players who were in both the 1999 Pacific Coast League and 2000 American League hit for a composite EqA of .290 in 1999 and .246 in 2000, which suggests that the AL was 44 points "harder" than the PCL.

Players who went from the 1999 International League to the 2000 AL had composite scores of .280 and .250: only a 30-point drop. That suggests the IL is closer to the AL than is the PCL.

Here are all the transitions for the last three years:

                       PCL              INT
1999 x - 2000 AL    .290-.246, -44   .280-.250, -30
1999 x - 2000 NL    .287-.243, -44   .275-.247, -28
1998 x - 1999 AL    .287-.246, -41   .291-.252, -39
1998 x - 1999 NL    .274-.241, -33   .278-.254, -24
1997 x - 1998 AL    .291-.250, -41   .278-.257, -21
1997 x - 1998 NL    .282-.245, -37   .276-.241, -35

In all six cases, the IL has a smaller dropoff than the PCL, by an average of 10 points. In five out of six cases, players from the IL performed better than players who had graduated from the PCL, by an average of five points. That's the evidence behind the claim.

It is certainly possible that there is no difference between the two leagues, qualitatively. I have not thoroughly checked for possible biases; perhaps the range in hitters' parks in the PCL, compared to the more equal parks of the IL, has an influence? Perhaps the IL players are a little older than the PCL players? Do the larger number of NL teams in the PCL mean more pitchers hitting, which skews the league totals?

There are lots of perhapses, and they may even be true, but the simplest explanation for the effects we see is that the IL is a little tougher than the PCL.

Here's another way of looking at the problem:

                        PCL                INT
1999 EAS - 2000 x    .275-.263, -12     .277-.262, -15
1999 SOU - 2000 x    .275-.264, -11     .277-.257, -20
1999 TEX - 2000 x    .285-.262, -23     .268-.237, -31

1998 EAS - 1999 x    .270-.249, -21     .284-.263, -21
1998 SOU - 1999 x    .285-.273, -12     .278-.258, -20
1998 TEX - 1999 x    .282-.260, -22     .274-.259, -15

Coming at it from the other direction, players from the same league drop off more going to the IL than the ones going to the PCL, again indicating that the IL is tougher. The Texas League data is the least reliable here, because almost all the teams have been paired with PCL franchises in Triple-A. Only 19 players went into the TL-IL samples, against 113 in the TL-PCL group. The Eastern (65 PCL, 119 IL) and Southern (68 PCL, 100 IL) samples weren't nearly as unbalanced.

Clay Davenport is an author of Baseball Prospectus. You can contact him by clicking here.