Quick Glance At Double-A Pitchers For The Pittsburgh Pirates

With Mitch Keller pitching a gem the other night, I thought it would be good time to give a quick glance at how the Double-A pitchers are doing overall.

You can’t scout a minor league stat line, prospects are often working on things and developing.  Perhaps a pitcher is working on developing a pitch and is having some troubles in the results department, scouting the line won’t show you that.  That’s where knowing the prospects and seeing them (especially in person) is a big factor.

But, for a quick glance to see how prospects are performing, using z-scores in some areas can provide a picture for how a prospect is performing.  It’s essentially a Sparknotes form of Kevin Creagh, from The Point of Pittsburgh, Stat Scout Line, though this is used more for in the present than creating a future value going forward, which is what the Stat Scout Line (SSL) is intended for.

For pitchers I looked at age, ERA, strikeout rate, walk rate, groundball rate, and swinging strike rate using the data provided by Fangraphs.  From there, I calculated the league averages and standard deviations for each of the measures above for pitchers under the age of 26.  They resulted in the following:

*Note: Groundball rate was taken by multiplying groundball rate by (TBF-BB-HBP-SO) to get groundballs and batted ball events and dividing the sum of groundballs by the sum of batted ball events*

Using the above, z-scores (or how many standard deviations from the mean) can be calculated for each of the pitchers.  For the age, ERA, and walk rate I multiplied the z-score by negative one since being below average in those areas is better, i.e. Mitch Keller’s 2.72 ERA is better than the league mark of 3.97 but has a negative z-score (this multiplication helps for summing the numbers).  Here’s pitchers in the Pirates system with five or more outings:

Looking at the components, must of the Pirates are young for the level (keeping in mind this is limited to players under the age of 26).  But they also don’t bring in the strikeouts, with only Montana DuRapau and Jesus Liranzo being past one standard deviation in strikeout rate and swinging strike rate.  DuRapau only pitched seven innings and is already 26, just squeezing into the threshold.  Liranzo pitched in nine games and is 23.

Hearn is close, having a good strikeout rate and swinging strike rate, and he’s around league average in the walk rate, and that’s before his seven shutout, no walk, and seven strikeout performance in last night’s game.

Brubaker stands out with his groundball rate (63.8 percent), and he was 1.49 standard deviations above the mean.  He projects as a middle relief candidate with a fastball and slider candidate.  Mitch Keller is the only other one to point out, and his numbers seem less than exciting outside of his age and groundball rate.

Here’s the sum of the Curve’s z-scores:

Brubaker and Liranzo are no longer in Altoona, leaving Keller at the top of the Pirates leaderboard.  Keller, including those who have moved up, ranks 37th of 242 players to face at least one batter.  Part of that is the walk rate, his lacking in swinging strikes, and strikeouts in general, all three being around the league mark.

The interesting name is Geoff Hartlieb, a 24-year-old relief pitcher who was a 29th round pick in 2016.  He has a 28.5 percent strikeout rate, 5.2 percent walk rate, and 64.4 percent groundball rate, with the groundball rate being 1.5 standard deviations above the mean.  His downfall is the 5.13 ERA, which should be lower based on the underlying numbers.  In his time in Pittsburgh, he has over a 50 percent groundball rate.  Perhaps an intriguing relief prospect.

Next: Bucs Walked Off By The Mets

Of course, it would be foolish not to mention the downfalls.  This method doesn’t account for all the things making a pitcher pitch well; quality of stuff, opponent, etc.  Nor does it narrow it down to only prospects, just an arbitrary age limit that allows some rehabbing major leaguers onto the list.  It’s also not park adjusted, which is important especially pertaining to ERA, one that with Baseball America’s park factors could easily be added.  Which is why this is just a Sparknotes type for of the SSL.

This is meant as a quick glance to see how a pitcher for the Curve is performing.  Mitch Keller has performed well in ERA and he’s young, but the strikeout rate, swinging strike rate, and walk rate are underwhelming.  But that goes back to the beginning, without seeing the players perform, this is only good as a baseline type and for a sum of how they’ve performed.

*Numbers entering games June 26