That very same fielding- and ballpark-independent statistical evaluation system that I have been using to rate the 2013 performance of the organization's minor league starting pitchers can just as easily be applied to their redheaded pitching stepbrothers. The sole metholodogical difference is that these arms will be compared only to league peers who mostly worked in one- to two-inning spurts.
What the Scores Mean
"Performance Score" amounts to the pitcher's overall grade relative to other league relievers. The first step is to sort the plate appearances against each league pitcher into 12 possible outcome categories [walk or hit-by-pitch, strikeout (K), infield flyball (IFFB), groundball (GB) to batter's pull-field third of the diamond, GB to center-field third, GB to opposite-field third, line drive (LD) to pull-field third, LD to center-field third, LD to opposite-field third, outfield flyball (OFFB) to pull-field, OFFB to center-field, OFFB to opposite-field]. Then, for each such event they allowed, the pitcher is charged with the average number of expected runs that the corresponding event was worth per that league's season (K or IFFB = very good, LD or pull-third OFFB = very bad). At that point, the relievers of a league can be ranked from best to worst in terms of expected run avoidance and their individual Performance Score is the number that expresses how well they fared overall relative to their peers.
To pinpoint each reliever's relative strengths and weaknesses (and better understand how they achieved their Performance Score), 3 subscores are computed to rate their performance versus that of league peers looking only at control (Control Subscore), strikeouts (Strikeout Subscore), or batted balls (Batted Ball Subscore). An Age Score is also tabulated to quantify how young the hurler was relative to the league's relief 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. For those who pitched for multiple affiliates, the scores calculated for each stop are averaged out based on the number of batters faced in each league to arrive at a single value for the year.
In stark contrast to the most recent FanPost where 59 pitchers who were in the system in 2013 or 2014 qualfied as "starters" on the basis of averaging 10 batters faced per game during the 2013 minor league campaign, only 33 pitchers qualify here as a "reliever" on the basis of facing less than 10 batters per game (at the same minimum batters faced total of 100). This organizational bias towards longer pitching appearances is a natural offshoot of 8 out of 13 pitchers on a full-season staff working in the tandem rotation system for the first 3 months of the season. As before we'll only be reviewing minor league data that was accumulated above the Gulf Coast League affiliate during 2013.
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"). Asterisks indicate lefthanded throwers. A red line has been stricken through the names of those who were no longer in the organization as of the time of this post.
Below are the scores of the 33 relievers, sorted from best to worst per Performance Score. Tyler Brunnemann, the club's final 2013 draft selection (1187th overall), nipped Gonzalo Sanudo by a few tenths of a point for top honors. Brunnemann threw 87 to 89 mph fastballs, a handful of slow curves, and a couple of changeups over a 5-batter stretch that I witnessed firsthand in September; Sanudo's fastballs were in the 90 to 92 mph range that same evening, with 2 slow curves and 1 changeup mixed in with 13 fastballs. There had been some chatter heading into the spring about the Astros considering placement of Sanudo in an A ball tandem rotation this April, so we'll soon see if that comes to pass. Brunneman's high marks on the 3 subscores would seem to make him a better bet for success as a starter, but his limited fastball velocity would probably speak against that being sustainable over the longer haul. Though Christensen looks like a carbon copy of Sanudo per the table numbers, he's a funky sidearmer and thus likely relegated to short relief. I had two looks at Andrew Walter over 3 July games and exited that series impressed with his 91 to 93 mph heater and hard curve; he might slot nicely into a tandem if his arm health will allow longer work (he did throw a changeup in his warm-up sequence).
Peter Moylan and his elbow may have already come and gone, but his 69 AAA Batted Ball Subscore emphasizes just how well he would have fit aboard the offseason train of thought that carried free agent groundballers Qualls and Albers back to Houston. Josh Zeid and Kevin Chapman both show potential here to fare better on strikeouts and much better on batted balls than they did in their brief big league debuts. I never appreciated how young Travis Ballew was for a California League reliever - he has time on his side to go along with how well his plus fastball velocity and quality slider pair up to boost his strikeout totals. The March release of Charles Basford (acquired in the June trade of Fernando Martinez) is a minor surprise given how well he meets the batted-ball-outcomes-biased statistical profile. Groundball extremist Pat Urckfitz (67% of batted balls were of that variety) posted the best Batted Ball Subscore and worst Strikeout Subscore of these 33 relievers. The trio of southpaws at the bottom saw their stock decline versus 2012, particularly Kenny Long who never recaptured the magic with his slider that had several of us thinking an offseason earlier that the (mostly) sidearmed one-pitch wonder was on the fast track to getting a taste of big league LOOGY action.
More generally, one can appreciate from the sheer number of redlined names in the table just how difficult it is to remain employed as a short reliever in the Astros' farm system with the tandem setup in place at just about all levels for the bulk of the season. These hurlers aren't just competing among themselves for a rather limited number of jobs but also with swingmen who are unable to pin down a full-time rotation spot.