How Performance is Graded
The Fielding and Ballpark Independent Outcomes evaluation system charges each minor league pitcher with the number of runs shown in the table below for each such event they allowed in each league (bunts, foulouts, and plate appearances with a pitcher batting are ignored). Summing that over all 12 event types and dividing the result by the number of batters faced yields a single number of runs per plate appearance that quantifies how well the pitcher should have performed in that league. Each pitcher then gets graded versus a core group of starting-biased pitchers in that league who met some minimum batters faced criteria. At that point the pitchers of a league can be ranked from best to worst on performance and they receive a Performance Score that expresses how well they fared. Note that whether an individual pitcher surrendered a hit, home run, or runs on a plate appearance is completely ignored in grading their performance.
The performance of each pitcher can be broken down into three sub-categories to identify their relative strengths and weaknesses: Control Subscore, Strikeout Subscore, and Batted Ball Subscore. Those 3 elements explain 23%, 43%, and 34% of a pitcher's Performance Score, respectively, in a typical league. An Age Score is computed to quantify how young the pitcher was relative to league starting-biased pitchers; this is used purely as a frame of reference when interpreting a pitcher's results.
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.
The pitchers whose names appear in the tables that follow averaged at least 10 batters faced per game in April, and thus qualify as "starting pitchers" for the sake of the analysis. Table values that bettered the league average mark 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").
Corpus Christi Hooks
Shirley and Rodgers ranked 1st and 3rd among the 41 qualifying Texas League starting pitchers, with someone named Gray between them. Shirley was elite in April at all 3 facets of pitching measured here. Rodgers was essentially the same pitcher in April as he was in 2013. Cruz still rates well but not nearly as well as he did over his equally brief 2013 finish at the same level. West's strikeout rating has dropped quite a bit versus his 2013 California League number.
The table below shows the breakdown of each hurler's batted balls for April.
Shirley's phenomenal 68 Batted Ball Subscore is mostly a product of an 67% overall groundball rate and almost no aerial pulls; the groundballs could be a new and promising development as his 2013 rate was but 45% in the California League. Rodgers earned his strong 59 Batted Ball Subscore via a similar pathway as Shirley.
Oklahoma City Red Hawks
Owens has gotten off to a nice start after missing nearly all of 2013 with a foot/ankle issue. Buchanan may also be performing better than we realize. Martinez is holding steady versus the 2013 numbers. With his 6-inning 12-strikeout performance of May 5, Foltynewicz is likely back up to the neighborhood of his 2013 numbers. Tropeano's strikeout rating has fallen and that figure needs to rebound given how important that parameter stands to be to his success. Doran's rough start seems to stem from a decline in his strikeouts and batted ball performance.
Buchanan's 67 Batted Ball Score is buoyed by a 65% overall groundball rate. Tropeano stands to have been fortunate on his actual April batted ball outcomes given the high 16% frequency of pulled outfield flyballs.
Top Organizational 8-Man Rotation for April
These would be the best 8 performers for April across all 4 full-season affiliates, according to the system.