What follows is how the Astros' 2013 starting-biased pitchers of the AAA Oklahoma City club performed versus their Pacific Coast League (PCL) peers, as judged by the Fielding and Ballpark Independent Outcomes system which I have been publishing data from here at The Crawfish Boxes. A more detailed explanation as to how the scores are computed can be found in this prior FanPost. Oklahoma City becomes the sixth and final organizational affiliate to be put through this statistical wringer, joining Corpus Christi, Lancaster, Quad Cities, Tri-City, and Greeneville.
What the Scores Mean
"Performance Score" amounts to the pitcher's overall grade for the PCL portion of their season relative to other league starters and is evaluated over every plate appearance that did not result in a foulout or bunt or feature a pitcher batting. Its computation assumes that the 2013 PCL-average effect on run expectancy occurred in every instance of each of 12 possible plate appearance outcomes:
- walk or hit-by-pitch = +0.33 runs
- strikeout = -0.30 runs
- infield flyball = -0.28 runs
- groundball (GB) to batter's pull-field third of the diamond = -0.09 runs
- GB to center-field third = -0.02 runs
- GB to opposite-field third = -0.08 runs
- line drive (LD) to pull-field third = +0.39 runs
- LD to center-field third = +0.36 runs
- LD to opposite-field third = +0.29 runs
- outfield flyball (OFFB) to pull-field = +0.39 runs
- OFFB to center-field = +0.02 runs
- OFFB to opposite-field = -0.02 runs
The three performance subscores (Control Subscore, Strikeout Subscore, Batted Ball Subscore) quantify how the pitcher would rate versus league peers looking only at control, only at strikeouts, or only at batted balls (reverse engineering the Performance Score metric for this league reveals that it is influenced 44% by Strikeout Subscore, 33% by Batted Ball Subscore, and 23% by Control Subscore). Age Score is tabulated independent of the performance measures and simply quantifies how young the pitcher was relative to the league starting pitcher sample. A 50 score on any measure amounts to matching the league's average value (the pitcher topped or equaled 50% of peers), a 60 amounts to 1 standard deviation (SD) better than league-average (topped/equaled 83% of peers), a 70 amounts to 2 SD better than league-average (topped/equaled 97% of peers), a 40 amounts to 1 SD worse than league-average (topped/equaled 17% of peers), and so on with any 10 point swing in a score amounting to 1 SD.
In the tables that follow, values that bettered the league average by at least 1 SD are highlighted in green text ("very good") whereas those that trailed it by at least 1 SD are in red ("very bad"). Asterisks indicate lefthanded throwers. The 10 pitchers in bold were among the 118 official qualifiers for the study pool in so much as they faced at least 200 batters in the league while averaging at least 10 batters faced per game (non-qualifiers do not enter into calculation of the means and standard deviations that are used to assign scores to pitchers). As recent acquisitions Collin McHugh and Anthony Bass each spent the bulk of 2013 in the PCL, their data has been included.
Peacock and Oberholtzer rated among the league's elite at Performance Score, placing 4th and 5th, respectively. LeBlanc rated well per this system during his brief tenure with the club after being claimed off waivers. Cosart also fared well in posting the PCL's 15th highest Performance Score by a starter; surprisingly, he was eclipsed by Oberholtzer for club Batted Ball Subscore honors. The red Batted Ball Subscores of McHugh, Wojciechowski, and Bass suggest that the trio would be at an elevated risk of incurring trauma when big league batters put their pitches into play.
The next table shows how each pitcher's event frequencies sorted out. Oberholtzer's club-high 67 Batted Ball Subscore was fueled by an extreme avoidance of line drives and an above-league-average rate of groundballs. Cosart's 65 Batted Ball Subscore was mostly the product of a ridiculous groundball rate and being difficult to pull when the ball was lofted in the air; a minuscule 1% infield pop up rate brought him down a bit in that department. McHugh's bugaboo on batted balls was a high line drive rate - a result that at times can simply be a matter of bad luck. Wojciechowski's was an extremely high rate of pulled outfield flyballs; repeating that sort of outcome in MinuteMaid Park would spell trouble for the troubling to spell pitcher.
And below are the LHB splits data and the RHB splits data of the 10 qualifiers, again graded relative to the corresponding numbers of their PCL peers. You may recall from the similarly-crafted American League Fanpost that, as major leaguers, Peacock was an extreme "forward splits" pitcher (36 LHB Performance Score, 62 RHB Performance Score) while Cosart was an extreme "reverse splits" pitcher (60 LHB Performance Score, 19 RHB Performance Score). And that now seems curious from standpoint that Peacock was one of the strongest pitchers in the PCL versus LHB while Cosart was among the top PCL pitchers versus RHB. Cosart's RHB Strikeout Subscore plummeted by nearly 5 SD from 69 in AAA to 22 in MLB play. Oberholtzer was fairly similar against LHB and RHB in the PCL, though he K'ed righties more frequently.
Buchanan's AAA LHB and RHB subscores are rather close to his AA ones, with the RHB Strikeout Subscore being more than 1 SD higher at the AAA level. The righty McHugh was considerably better against LHB than RHB and posted one of the PCL's poorest Batted Ball Subscores against RHB. Bass would be expected to struggle with MLB LHB given the poor Strikeout Subscore and lowish Batted Ball Subscore he posted against PCL LHB.
MLB vs AAA: Peacock, Oberholtzer, and Cosart
Given that the trio stand to face a better caliber of hitter and be compared to a more talented peer group of starting pitchers in the majors, one would naturally expect their Performance Scores and subscores to decrease relative to their AAA marks. And perhaps even more so in that 2013 marked their first extended taste of big league action.
And that is generally what the table shows. Oberholtzer's Control Subscore and Cosart's Batted Ball Subscore were the only two subscores that were better in the majors than minors. Peacock and Oberholtzer each saw their Strikeout Subscore decrease by about 1 SD (10 points) in the majors relative to their AAA mark. The other 5 subscores decreased by closer to 2 SDs, emphasizing just how difficult that initial transition to major league competition can be. While many of these AAA subscores would be difficult for the pitcher to match as a big leaguer, the values do cast a bit of a spotlight as to where we might look for improvement as the trio gain more major league experience.