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Translating Minor League Performance: A Wonderful Tool

Preston Mattingly of the Class A Inland Empire 66ers hits against the High Desert Mavericks in June.
Preston Mattingly of the Class A Inland Empire 66ers hits against the High Desert Mavericks in June.

The jump from the minor leagues to the major leagues is difficult to predict, at least on an individual level.  Evaluating minor league performance requires context, and the better organizations are great at it.

Dan Szymborski has provided baseball fans with a labor of love.  Szymborski, who is the Transaction Oracle for Baseball Think Factory, has delved into the data, and calculated the Major League Equivalencies (MLEs) for every minor league season dating back to 1978.  Using park and league factors, Szymborski was able to translate these minor league seasons into an estimate of what would have happened in the major leagues.  These are extremely useful in identifying some overrated seasons, or some that have flown under the radar.

Translating MLEs is not an exact science.  Kevin Johnson of had as good an explanation as any of why MLEs are useful:

Of course, creating MLEs at all is a bit of a fool’s errand. We can’t really know how any player would have played in a different environment, especially one that is drastically different regarding its level of competition. Some players can adapt and adjust their playing when faced with different settings, and some have difficulty. Nevertheless, it can be a fun and enlightening exercise. For current baseball players, MLEs can also be used to build predictive models of future play results. This is really what James had in mind — a way to use past non-major league data to predict future major league performance of young players by converting that non-major league data into data that would approximate MLB level play, then use that data along with any MLB historical data on the player to give a greater sample size on which to make predictions.

Here are some notable minor league seasons in the last three decades of Dodger minor league baseball.

Mike Marshall, 1981 Albuquerque Dukes

Actual Stats    34 137 .373 .445 .675 1.120
MLE 24 88 .278 .336 .476 .812

The 21-year old Marshall put up one of the most storied seasons in Dodgers' minor league history, and had an enormous amount of expectations heaped upon him.  However, Albuquerque is a town a mile above sea level, with one of the most hitter friendly environments in baseball.  Marshall had a nice career as a Dodger -- over 900 games with a 117 OPS+ -- but he is largely viewed as a disappointment.  I have to think if that 1981 season was viewed in proper context, Marshall wouldn't have suffered under the weight of unrealistic expectations.

Sid Fernandez, 1983 San Antonio Dodgers

Actual Stats    153 13-4 5.6 12.3 2.82 1.353
MLE 148 10-7 5.7 9.3 3.59 1.453

Not bad for a 20-year old in Double A.  The Dodgers thought so highly of Fernandez that they traded him with Ross Jones for Bob Bailor and Carlos Diaz.

Ramon Martinez, 1989 Albuquerque DukesAlbuquerque Dukes

Actual Stats    113 10-2 4.0 10.1 2.79 1.257
MLE 110 7-5 4.2 7.6 3.35 1.327

The 21-year old Martinez also had 15 starts at the major league level in 1989, with a 3.19 ERA and 1.216 WHIP, an improvement on what his minor league numbers earlier in the season suggested.  Martinez would win 20 games the next season, still the last season a Dodger pitcher has won 20 games.

Paul Konerko, 1997 Albuquerque Dukes

Actual Stats    37 127 .323 .407 .621 1.028
MLE 23 88 .273 .345 .460 .805

The 21-year old Konerko produced similar stats to the Dodgers' incumbent first baseman, Eric Karros, who hit .266/.329/.459 with 31 home runs and 104 RBI.

Ivan DeJesus, Jr., 2008 Jacksonville Suns

Actual Stats    91 76 .324 .419 .423 .843
MLE 80 58 .268 .348 .357 .705

That on-base percentage as a 21-year old was plenty reason to be excited about DeJesus's potential.  His broken leg set back his development, but the talent is still there.  He is still a big part of the Dodgers' future.

There are plenty of seasons to find.  Be sure to click through to Baseball Think Factory if you want to download the Excel files with all the glorious data.