Marlins trades show one way to evaluate Minor Leaguers

In completing two blockbuster trades this week, the Marlins netted themselves four young arms in exchange for two of their marquee players. To the fans sitting at home, these trades reek of desperation. The Fish, World Series champions just two seasons ago, traded proven fan-favorites for a bunch of guys who played in places like Wilmington, Delaware, and Norfolk, Virginia, two towns hardly known for their baseball.
For those of us who don’t scout Minor League teams for a living, these names heading down Miami’s way don’t lend much hope. Sure, Hanley Ramirez’s name may have made it into the baseball collective and Ani Sanchez or Yusmeiro Petit may ring a few bells. But they don’t carry the gravitas of a Carlos Delgado or Josh Beckett. How then can fans at home who simply have Baseball America’s prospect reports and stats from The Baseball Cube on hand evaluate these players?
One of the challenges facing the numbers-based community has long been projecting Minor League prospects to the Majors and beyond. Fans don’t have access to scouting reports detailing control, poise, build, and all of the other ways in which scouts have long evaluated young players. We do, however, thanks to the Internet have access to stats that can help us see how these young players may fare, and these stats aren’t even obscure.
For Minor Leaguers, two of the best indicators of future success are control and power. Is a young pitcher missing bats while hitting the strike zone? Luckily, strike out rates and walk rates can go a long while toward answering that question.
Let’s look at how the Marlins’ new young guns have done in these two categories throughout their careers.

Age K/9 IP BB/9 IP
Yusmeiro Petit (AAA) 21 11.16 1.95
Anibal Sanchez (AA) 21 10.98 2.92
Jesus Delgado (A) 21 7.14 4.42
Harvey Garcia (A) 21 9.06 3.88


From this table, it seems as though the Marlins got two legitimately great prospects (Petit and Sanchez), one fringe prospect (Delgado), and one borderline prospect (Garcia). For Garcia, his career progression shows promise. His K rate at Greenville was nearly 11 per 9 innings in 2005 and he cut his walk rut down to 3.63 per 9 innings.
What then makes these metrics good or half-decent indicators of future success? Most notably, they are defense-neutral. We’re not relying on the sketchy fielding of Minor League players to prop up or put down a prospect’s ERA. Second, these numbers suggest that a pitcher can control the strike zone. As a pitcher progresses through the Minors, hitters get better. If these pitchers can continue to rack in strike outs while avoiding walks, this shows that a pitcher can effectively throw strikes. While Petit struggled in 14 AAA innings this year, he still managed a strike out an inning. Numbers like those suggest that the 9.20 ERA he suffered through at the end of the season will go down.
How do these numbers then project to the Majors? That has long been an issue. In a piece from 1998, David Luciani looked at how Minor League performance at the AAA level projects to the Major League level. Notably, he found that a pitcher’s Major League strike outs were 75 percent of his AAA levels and walks were around 125 percent. These numbers however don’t tell us much about guys pitching at A or AA.
In the end, Minor League numbers can only tell so much. They don’t always project well to the Majors, and sabermetricians are stilling trying to find ways to figure out Major League success from Minor League success. This is just another example of where scouting needs to mix with statistics. It pays to see how fast a pitcher throws. He pays to see his command with runners on base, his make up and stuff. We, sitting at home with just numbers, can only understand so much.
But what we do understand shows us that the Marlins, in addition to a first baseman, outfielder, and short stop prospects, may have netted themselves two potential big league starters and two guys who may just fill out Minor League rosters.

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One Response to Marlins trades show one way to evaluate Minor Leaguers

  1. h-town says:

    trade d-train to astros

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