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Adjusting for dorkcosity . . .

What would some schlub from the Eastern League hit if you plunked him---and his season's worth of statistics---in the National League? Hell should I know, but it's a fun exercise and, I suppose, a potentially rewarding one. In fact, in his final essay in the Baseball Abstract line of books, Bill James opened the list of principles he had learned in his sabermetric career with the following statement:

Minor league batting statistics will predict major league batting performance with essentially the same reliability as previous major league statistics.

Of course, the unstated proviso in the quoted sentence is "properly interpreted," as clearly minor league contexts are distinguishable from big league ones. To that end, James developed what he termed "minor league equivalencies," or MLEs. These days, the abbreviation "MLE" seems more closely associated with major learned equivalencies, but the concept is identical: a translation of what the major league equivalence of what a player actually did that, like actual MLB statistics, contains some degree of predictive value.

Nearly a decade ago, Dan Szymborksi of the Baseball Think Factory website wrote a primer on how to calculate MLEs (see previous link), in which he walked through a step-by-step calculation of 1997 MLEs for Paul Konerko (who you may have heard of, if you follow baseball) and Danny Clyburn (who you may have forgotten, unless you follow rap sheets). Generally speaking, Szymboski recounted the following steps:

  • Take the raw statistics
  • Adjust for the league (e.g., the Pacific Coast League, a high-offense league) and the home park (e.g., Albequerque, a high-offense park)
  • Adjust for the caliber of competition (e.g., the difference between Triple-A and MLB)
  • Adjust for the park factor of the corresponding major league ballpark (so as to provide a translated offensive environment)
  • Adjust the component stats (from hits to at-bats, and everything in between) accordingly.
  • Fill-in-the-blanks, and there you go.
At any rate, Szymborski's MLE walk-through adjusted Paul Konerko's 1997 season at Albequerque of the PCL, in which he hit .323/.407/.621, to a translated .248/.312/.441 season at Los Angeles. Quite an adjustment, no?

Lest one believe that adjustment was overly punitive, as a twenty-two year-old rookie for two NL teams in 1998, Konerko hit .217/.276/.332. Konerko would subsequently go on to better things, of course.

* * * *

Well, enough theory. Szymborski is still at it, and though I'm not going to go as far as to provide a warranty for his methodology, I thought it would be instructive to take a look at what his work says about the Nats' minor league system.

First, let's take a look at his minor league park factors. There are both one-year and three-year weighted park factors. For instance, Double-A Harrisburg provides the following one- and three-year factors:

Runs Home Runs
0.96 1.28
1.01 1.21

Thus, in both cases, the Harrisburg offensive environment is pretty close to the Eastern League average in run-scoring but substantially above the league average in home run-hitting.

As noted, these park factors are helpful for accomplishing the second task, which is actually making the MLE translations. Szymborksi's spreadsheet can be found here and, speaking of the Eastern League, it might be instructive to look at the MLE of one of its 2006 stars, Kory Casto:

Which Casto? AVG/OBP/SLG HR, RBI
2006 EL, Actual .272/.384/.468 20, 80
2006 MLE, Translated .227/.325/.364 12, 56


Now, does this mean that, if you plunked Casto in the National League in 2007, he would post a sub-.700 OPS? It's possible, certainly, but not necessarily so. Remember, the MLE is a translation, not a prediction, and it doesn't factor in any potential improvements Casto will make in the Arizona Fall League (including, perhaps, solidifying his skills versus lefthanded pitching). Although he doesn't have a top prospect's youth at his side (as Konerko did in '97-98, for instance), it's conceivable that Casto will continue to improve his hitting stroke. But the thrust of this analysis is that Casto, at this point, seems stretched offensively for a corner outfielder.

Or, for another example, what about the Triple-A affiliate, New Orleans of the PCL? Again, let's take a look at one- and three-year park factors:

Runs Home Runs
0.82 0.69
0.82 0.69

Well, that's rather uncanny. In fact, it makes me wonder whether one set of numbers is erroneous. At any rate, while I'm digressing, I'll state the obvious, that there are more park factor elements than runs scored and home runs hit.

Anyway, the suppressed offensive park factors seem to bode well for a Nats' hitting prospect there like, say, Larry Broadway. And it's true: As far as the PCL goes, New Orleans offers a poor hitting environment---and that benefits one's MLE. But the inquiry doesn't end there. The PCL, as a whole, is a very good offensive league. Moreover, as noted previously, MLEs adjust for the caliber of competition within a league. According to Szymborski, Triple-A's caliber is about three-quarters to that of MLB. (And it stands to reason that Double-A's caliber is even worse, further suppressing Casto's MLE.) Broadway's corresponding MLE must reflect this:

Which Broadway? AVG/OBP/SLG HR, RBI
2006 PCL, Actual .288/.356/.455 15, 78
2006 MLE, Translated .272/.322/.421 13, 62

As we can see, Broadway's MLE numbers aren't docked too much from his actual numbers. It's basically the cost of the competition adjustment, because Broadway's home offensive environment was already suppressed (relative to his league) to a great extent (and, intuitively, a guy who hits fifteen homers in the PCL doesn't seem like a guy who would put up huge power numbers, unless he's young for his level or is coming off injury or somesuch). On the other hand, if we go back to Casto's MLE, we see that his translated numbers are reduced both by the caliber of the competition and by the home park; look at how much playing in a good home run park cuts into the MLE's isolated power, for instance.

Well, that's a look at MLEs---take-'em-or-leave-'em, or split the baby and keep 'em in the back of your mind this offseason. You can do the same for pitchers, too, but I'm too lazy to do so, and this organization doesn't have many pitching prospects anyway.