clock menu more-arrow no yes mobile

Filed under:

Statistical Prospect Evaluation Primer: Part 1, Context

Over the course of the spring, I have often commented that Chris Getz has built a minor league track record which forebodes future major league success, but I've never gone into specific detail to explain. I thought I'd put together a bit of a primer on the things I look for when evaluating minor league prospects.

First things first, there is no substitution for scouting. You can tell quite a bit about a player by studying their stats, but you'll never get the full picture without observing them in the field. Scouts rate offensive players 5 tools (current and future) on a 20-80 scale. Those 5 tools are listed below, and discussed more in-depth in this scouting primer.

  1. Hit for average
  2. Hit for power
  3. Speed
  4. Arm
  5. Defense

The information collected by those gray haired, radar gun wielding guys will never be without use. No matter how far computers and statistical evaluation advance, there will always be a need for scouts.

But you, the better-than-average fan, whose scouting acumen consists solely of reading Baseball America, Baseball Prospectus or this site, can gain a rather deep understanding of a prospects development simply by knowing what to look for when gazing at a prospects stats. Here's how.

Age vs. League

While Age vs. League is not the most important factor in statistical-based prospect evaluation, it is, however, the first thing I look at when I first take a look at a prospect's numbers. A player's age vs. his competition level gives context to their stats.

As a very general guideline I like to use the following progression for a player:

  • AAA -- 23
  • AA -- 22
  • A+ -- 21
  • A -- 20

If you'll notice those ages are considerably younger than the average ages of each respective league. That's because most players in professional baseball will never reach the major leagues. And when we're talking about prospects, we're looking to identify future major leaguers.

A player with a solid minor league record posted at the above ages and levels would most likely be considered a prospect, maybe not an elite prospect, but the type of player you can reasonably expect to become a major league regular in the future.

Players who are a year or two younger than the listed age at each level, while still producing adequately, are usually projected to be future stars. There's a reason most Hall of Famers hit the major leagues before age 21.

On the other side of the coin, a player who is a couple of years older than the ages listed above shouldn't be completely ignored, but you need to take their age into account. If I see a 23 year old dominating in Winston-Salem (A+), for instance, I'd like to see him promoted more quickly than a younger player with similar production; make him prove his production at a higher level

League and Park Factors

Read enough prospect reports and you're bound to come across phrases like the Florida State League is a pitcher's league or the PCL is a hitter's paradise. What those statements refer to are the different hitting environments of those specific leagues. For instance, according to Baseball-Reference, where you can view all league averages since '92, the International League, which contains the White Sox AAA affiliate Charlotte Knights, had an average line of .263/.331/.404 compared to the .277/.348/.444 composite line from the much more hitter friendly PCL.

In addition to league factors, you should also remain acutely aware of the home park factors that can influence a player's performance.

                         R       H      2B      HR      BB       K
Charlotte (AAA)       1.05    1.00    0.98    1.37    0.96    1.00
Birmingham (AA)       0.92    0.97    0.87    0.82    0.97    1.03
Winston-Salem (A+)    1.05    1.03    1.06    1.06    1.03    0.98
Kannapolis (A)        0.98    1.00    0.99    0.93    0.96    1.00

The White Sox have two very extreme parks (at opposite ends of the spectrum) in the high minors. Charlotte has tiny power alleys and greatly inflates homeruns, while Birmingham has expansive power alleys and plays as one of the stingiest home parks in the entire minor leagues.

Once you give the stats their proper context, you can take dive headlong into the peripherals which make up the bulk of statistical-based prospect evaluation, which I'll tackle in part two...