I conducted a statistical review of how 2012’s minor league lefthanded pitchers (LHP) performed against lefthanded batters (LHB) and published the complete results over at the SBNation site MinorLeagueBall. All LHP who had faced at least 40 LHB above the Low Rookie level (Gulf Coast League and Arizona League) were included (547 LHP total). The methods used are explained in great detail there. In short, I compared each LHP versus their league peers (specifically league averages for LHP vs LHB) on four metrics: 1. strikeout percentage (K%), 2. walk and hit-by-pitch percentage (BB&HBP%), 3. batting average against on batted balls (BABB), and 4. linedrive and outfield flyball percentage on nonbunted batted balls (LD&OFFB%). Based on how much each pitcher was better/worse versus league average in the relevant metric, they were assigned a score that ranged from 0 to 100, with 50 being average for a minor league LHP vs LHB, and each 10 points amounting to one standard deviation (SD, thus a 70 score is 2 standard deviations better than minor league average). Lastly a Composite Score was computed that took all 4 scores into consideration giving unequal weights to each (22% K, 10% BB&HBP, 29% BABB, 39% LD&OFFB) and another 0 to 100 score was obtained, again with 50 points being minor league average and each 10 points amounting to one SD. The motivation for all of that was to assess how Astros minor league LHP performed against LHB relative to minor league LHP in general, and that is what will be presented below. Some limitations of this approach are noted at the end of the original post, with perhaps the most important one being that the analysis was conducted on just one season’s worth of data.
Below are the results limited to Astros pitchers followed by snippets on some of them, working from the bottom of the list up (use Ctrl+ or Ctrl- to zoom in/out, if necessary). The Astros’ system fared very well in the Composite Score category in 2012 placing 2 LHP in the minors’ Top 10 and 7 within the Top 100 (tying Kansas City for the most of any MLB organization).
Shirley rates very well in the non-batted ball metrics (2 SD above average at strikeouts and nearly 1 SD above average at walks) and below average in the batted ball ones. With better batted ball outcomes moving forward, Shirley could perhaps establish himself as a viable major league relief prospect.
A prior unpublished analysis of mine of Corpus Christi relievers painted the March trade acquisition as being very slightly above average for a AA reliever against all comers in 2012, and this one shows him being average against LHP save for the BB&HBP control metric where he falls more than one SD below average (the lowest BB&HBP Score of the 24 Astros pitchers who qualified). Being about average at everything at the AA and AAA levels can keep a LHP gainfully employed for a handful of years and allow him to earn some major league service time, but it seems that Chapman will need to improve his control and distinguish himself as strong at some skill vs LHB if he is to stick in the big leagues.
Geith, acquired after the minor league season from the Rays to complete an earlier trade for Ben Francisco, rated one SD better than average at the avoidance of linedrives and outfield flyballs. With vs RHB and vs LHB data that seems to fit the profile of a starting pitcher, Geith could perhaps find himself inserted into a starting rotation at some point during 2013 if he has the stamina for longer work.
Lambson showed some positive traits for a lefty relief specialist being roughly 1 SD better than average at both K% and BB&HBP%.
Sogard rated 7th best across all minor league LHP in LD&OFFB% thanks to his 23% season rate but seems a bit of a one-trick pony, rating below average at the other 3 parameters. A pitcher with Sogard’s statistical profile would be slotted as a starting pitcher in many organizations.
True to character, Keuchel rated very well at BB&HBP% and LD&OFFB% (nearly 2 SD above average at each) and subpar at K%. In his first go at MLB LHB Keuchel’s K% dropped by a factor of nearly two versus his minor league rate (from 17% to 9%) while his BB(&HBP)% tripled (from 3% to 9%) and his LD&OFFB% increased slightly (from 33% to 40%). Some degree of movement back towards his minor league K and BB rates versus LHB should be expected in the big leagues during 2013. With poor minor league K% numbers vs LHB, relief doesn’t seem like a viable fall back option for Keuchel at this point.
Staying well under the radar of most followers of Astros minor leaguers, Meiners ranked 37th in Composite Score. He rated a half SD to one and a half SD above average at the 4 metrics and was particularly good at avoiding linedrives and outfield flies. As a 40th-round 2010 selection out of a small university who has been moved very slowly through the system and has pitched in just two games for a full-season club (Lancaster in 2011), the 24-year-old may still have to win a spot on a full-season roster in the spring and get off to a good start thereafter to cement a secure position on the organizational depth charts.
Cedeno placed 10th overall amongst minor league LHP and rated a percentage point or two above average at the non-batted-ball metrics and 1 to 3 SD above average at the batted-ball metrics. Relative to the AAA numbers, his MLB vs LHB data shows a huge increase in K% from 23% to 39%, a slight increase in BB&HBP% from 9% to 11%, a large and not entirely unexpected increase in BABB from .132 to .382, and a LD&OFFB% that dropped a few percentage points. Cedeno’s combined 2012 vs LHB data were promising altogether and bodes well for him landing a full-time job in the Astros’ 2013 bullpen. Cedeno repeating such a lofty K% versus MLB LHB in 2013 would be very surprising.
Long has earned far more than a snippet by ranking third overall in Composite Score and first overall in both K% and BABB. Here I want to re-emphasize that the BABB calculation doesn’t include the many outs that Long accumulated via the strikeout – he was the best LHP of 547 qualifiers at striking out LHB and amazingly was also the best of them at avoiding a hit when the LHB did manage to make contact, with the main caveat being that there were just 22 batted balls in his sample since he struck out so many. As seen in the graph below, Long uncharacteristically surrendered a line drive or outfield fly to 5 consecutive LHB during the California League playoffs (plate appearances 52 through 56 on the graph) causing his LD&OFFB% to jump from 37% to 52% and his K% to fall from 58% to 54%. That "slump" and/or the decision to include postseason data likely cost Long the number one ranking in this analysis, as his regular season LD&OFFB Score would have been closer to 60 than 40 and that alternate value would have boosted his Composite Score near 90 given the relatively large weight given to LD&OFFB Score in the Composite Score computation. That his LD&OFFFB% fell during his Tri-City tenure and rose during his Lancaster stint is intriguing and could perhaps be explained by increased usage of his knockout pitch, a sidearm slider, in California. On the plus side, Long’s K% vs LHB increased rather than decreased following his two-level jump from Tri-City to Lancaster.
The second highest 2012 K% vs LHB by any minor league LHP of any system was 41% and well shy of Long’s 53% figure. So what sort of historical company is Long keeping in striking out more than half of the LHB he faced? Given that minor league vs LHB splits are available dating back to 2005 from minorleaguecentral and the now-retired minorleaguesplits, I compiled the same stats for all of those seasons to identify other LHP who had struck out at least half of their LHB in a season using a similar inclusion criteria as above.
Long’s 4 recent predecessors in the single-season 50% club each went on to become big leaguers. Each features a slider prominently, save for the starter Pomeranz who throws more of a true curveball. Swindle would be the worst career outcome to date but continues to lurk in AAA, perhaps even representing Long’s floor as a professional given the similar pitch velocity profiles, heavy slider dependence, and sidearm delivery. Long’s ceiling seems difficult to pin down, particularly since he hasn’t shown any clear vulnerabilities to RHB yet and will even mix in a curveball and a closer-to-average-velocity-for-a-lefty fastball each thrown from a more conventional over-the-top armslot against them (Long provided a synopsis of his very unique pitch repertoire to What the Heck, Bobby here).
Despite possessing one of the most dominant pitches thrown to lefthanded batters in the minors today, Long figures to be viewed skeptically by many prospect evaluators due to the low- to mid-80s fastball that he throws from the same armslot as the wipeout slider. In spite of that, Long seems destined to be a big leaguer and soon. Just what variety of one will have to be discovered then as it would be difficult to project how big league hitters would fare against such a unique pitcher beforehand, though brief glimpses had in future spring trainings could provide some early clues.