Evaluating players in the major leagues tends to usually be easier than evaluating players in the minor leagues. This is because in the majors, we have less factors to focus on. Mainly league factors. In the majors, we have two league factors (we’ll use ERA for this), the American League at 4.37 and the National League at 4.34.
This becomes way more extreme in the minors. You’ll have a league that favors hitters strongly, such as the Pioneer League (Rookie) with a league wide ERA of 5.65. Then a league that favors pitchers like the Southern League (AA) with an ERA of 3.60. That’s quite a difference.
These differences have to be strongly considered when evaluating a prospect. For good measure, look at Idaho Falls Chukars pitcher Holden Capps. On the surface, a 5.49 ERA and 4.80 FIP does not look all that great. But because he pitched in the hitters paradise known as the Pioneer League, Capps was actually had a better season than two-thirds of the league.
Because I was so intrigued with this, I decided to fire up the Excel. I started by finding every qualified pitcher in the minors (over 2,700 pitchers). Every pitcher from the AAA to the Dominican Summer League. Using FIP as my stat of choice, I compared them to their respective league’s (Pacific Coast, Texas, Pioneer, etc.) FIP using standard deviation to create a z-score. Here’s what I got.
AAA- Omaha Storm Chasers
- Jake Junis comes up with the best number for any starting pitcher in the Royals system. Only two starting pitchers in the PCL had a better FIP than his 3.12 (Wilmer Font and Luke Weaver). His -1.82 z-score (value in the last column) also ranks in the top 3% in all of the minors.
- Eric Skoglund is a good example I can use. At first glance, his 4.46 FIP isn’t impressive. But.... his z-score is better than nearly 2⁄3 of all pitchers.
- Josh Staumont obviously had a rough time in AAA. His z-score of 1.72 ranks in the bottom 100 of 2,700+ pitchers.
AA- Northwest Arkansas Naturals
- Pedro Fernandez was very good in his 50.2 innings of relief with the Naturals, posting a 9.1 K/9 and 2.3 BB/9. His 2.33 FIP was very good for even the pitcher-friendly Texas League.
- Another reliever that had a very sneaky year was Tim Hill. Showing off some good peripherals, Hill might of had an unlucky year, as his ERA was almost two runs higher than his FIP. His z-score also came out nice, ranking in the top 3%.
- Foster Griffin, who some consider to be the Royals top pitching prospect, actually came out as below-average for the Texas League.
A+- Wilmington Blue Rocks
- Richard Lovelady was on another level during his time with the Wilmington Blue Rocks. His -2.90 z-score ranked #3 out of every pitcher.
- Though he was below-average in AA, Griffin was well above the league-norm for FIP in A+.
- Another top Royals pitching prospect had below-average numbers in a pitcher friendly league. Scott Blewett’s FIP of 4.23 was the worst mark on the team.
A- Lexington Legends
- The Lexington Legends had some pitching problems in 2017. As a team, they had a 4.72 ERA, worst in the South Atlantic League by a decent margin. The only pitcher above league standards was Jose Veras, a reliever who threw 55.2 innings in Low-A.
- Nolan Watson and his 5.41 FIP ranked in the bottom 1% of the minors.
Rookie- Idaho Falls Chukars
- The Pioneer League is by far the most hitter-friendly league. The league ERA is 5.65.
- 2017 32nd round pick Andrew Beckwith had a terrific 24.2 innings in Idaho Falls. Had a 3.22 FIP, 11.0 K/9 and 2.9 BB/9. His -1.72 z-score also ranked in the top 3%.
- 2017 8th round pick Holden Capps had a good debut. His -0.52 z-score ranked 2nd on the team.
Rookie- Burlington Royals
- The Appalachian League is the 2nd most hitter friendly league, trailing only the Pioneer League.
- 2017 6th round pick Tyler Zuber had a fantastic debut. In 25 relief innings with the Burlington Royals, Zuber posted a 1.82 FIP, 13.7 K/9, and 2.5 BB/9. His -2.23 z-score ranked second in the Royals system and 22nd overall.
Rookie- Arizona League Royals
- Playing in a league that favors hitters, Andres Sotillet put up good numbers, as his z-score ranked in the top 20% of Minor League Baseball.
- The only other player that posted an above-average FIP for the AZL Royals was 2017 18th round pick Marlin Willis, holding a 3.83 FIP in 21.1 innings as a starter/reliever.
Rookie- DSL Royals
- Delvin Capellan put up video game numbers in his first season of professional baseball (0.48 ERA, 1.94 FIP in 56 IP). Part of this has to do with the DSL strongly favoring pitchers though, with the league having an ERA of 3.63 as a whole.
- About half of the DSL Royals pitchers rated as above-average. They had a team ERA of 3.05, 7th in the DSL.
It is very important to understand these things too, because without context a person would think a 5.00 FIP in the Pioneer League would be underwhelming. Diving in deeper, we figure out that would be a very good mark, as only two qualified pitchers in that league posted a FIP below 5.00. The idea of this was to give a better perception on minor league numbers, as they are very unstable compared to those of the major leagues.