Astros Pitchers Helped By Elite Defense

2016 has been a tough year for the Astros' pitching.  Dallas Keuchel was Cy Young Award winner last year, but his results have been mediocre this season.  And to top it off, he was unavailable during a critical late season stretch, due to a shoulder injury.  Colin McHugh was a dependable No. 2 starter last year, but has suffered inconsistency this season.  Talented young Lance McCullers has been out due to injury for much of this season. Doug Fister had a good first half, but faltered down the stretch.  Ken Giles was an expensive acquisition to solidify the bullpen, but he had a terrible April--which happened to coincide with a terrible April for the whole team.  And the list could go on.

Yet, despite these problems, the Astros' team ERA ranked 10th in the majors. With its pitching ranked in the top one-third, somehow the Astros survived the pitching difficulties with more than respectable performance.   What is responsible for keeping the Astros' run prevention afloat?  I would start with underrated team defense.

For this article, I will use the Fielding Bible's Defensive Runs Saved (DRS).  The Astros use defensive shifts a lot.  Because DRS is the only advanced fielding metric which tracks team runs saved by the shift, DRS is more suitable than UZR. In a 2014 TCB article, I explained why DRS is preferable to UZR in examining the team defense of teams which intensively utilize shifts.  You can see basic team DRS data on the Fangraphs leaderboard.  This data shows the Astros second in DRS to the Cubs (+57 and +75).  But DRS for runs saved by the shift is not included on this leaderboard.  The shift DRS is available at Bill James on-line, which (unfortunately) is accessible only by subscription.

The following data, taken from Bill James' web site, shows the top two fielding teams in the NL (Cubs, Giants) and AL (Astros, Red Sox).

The inclusion of runs saved from the shift significantly reduces the gap between the top ranked Cubs and the second ranked Astros.  In the AL, the gap between the No.1 Astros and the No. 2 Red Sox is sizeable (almost 50 runs saved).  The Astros' DRA equates to approximately 9 wins above average.

Analysis of DRS by Position

Outfield defense (+41 runs) has been the most impressive component of the Astros' defense.  The strategy of playing three center fielders in the outfield at the same time has paid dividends.  The Astros achieved +18 runs saved in LF, which is easily the best LF defense in baseball.  Colby Rasmus and Jake Marisnick are primarily responsible for the LF runs saved.  George Springer has provided almost all of the RF fielding for the Astros, and the team's RF defense (+14) falls short of the Red Sox top ranking for RF (due to Mookie Betts).  The Astros produced +9 in CF, which is  notable, given that Carlos Gomez's stint in CF was not particularly effective (-5).    Marisnick and Rasmus again combined to produce the positive results in CF.

On the infield, shortstop (-3) and 1b (-1) are the only negative runs saved positions for the Astros--and the deficits are not particularly large.  (And keep in mind that the shortstop is involved heavily in shift plays, and runs saved from the shift are not attributed to any position.)  The pitcher (+16) and catcher (+6) show particularly effective defensive marks.

The fielding by Astros' pitchers has been almost spectacularly good.  16 runs saved is more than three times the runs saved by the next highest AL team.  Dallas Keuchel who holds two gold gloves is a large part of the fielding effectiveness (+7).  Luke Gregerson (+4) and Lance McCullers (+3) have also been excellent on defense.  The Astros have very few negative contributors to pitching defense (Scott Feldman is one of them, and he was traded at mid-season)  Given the Astros' overall good showing on pitching defense, presumably the Astros place a premium on pitcher fielding during spring drills.

Impact of Defense on Pitching Performance

The effect of defense  is reflected in team pitching ERA.  I attempted to estimate the benefit that the Astros' pitchers received from above average defense. I utilized the Astros' 86 defensive runs saved above average for the calculation. If the Astros had no defensive runs saved--i.e., a completely average defense--the RA/9 would increase from 4.26 to 4.84.  Assuming the same ratio between Astros RA/9 and ERA, the Astros' ERA with average defense is 4.59.  The impact on the Astros ERA ranking among all 30 MLB teams is shown below.

Current Astros rank and ERA

10th / 4.04

Astros rank and ERA with Average Defense

26th / 4.59

If the Astros were simply an average defensive team, the Astros' ERA would fall from a top 10 position to 26th.  This is a hypothetical calculation, but it demonstrates that the team's defensive prowess prevented the pitching staff from producing dreadful results.  (Note that this comparison assumes the accuracy of the Fielding Bible's defensive runs saved, which is a significant caveat.)

Conclusion

A team's runs allowed reflects the combined effectiveness of both the pitcher and the defense.  If the Astros intend on improving the pitching performance next season, it is important to avoid diluting the quality of the Astros' defense.  Fans may be hoping that the Astros acquire better hitters, but if those hitters are not good fielders, the "improvement" in terms of wins may evaporate.  Moreover, it is possible that the pitching staff results may improve next year as a result of continued improvement in defense.  The Astros are a relatively young team, and this normally means that the team's defensive results can improve with more experience.  For example, Carlos Correa is only 21 years old and has tremendous physical ability at the shortstop position.  My expectation is that continued improvement could eliminate the negative DRS at the shortstop position.  Yuli Gurriel could well produce positive defensive results at first base.  Alex Bregman has looked very good at 3d base, despite limited experience at the position, and the Astros DRS could improve if he plays a full season at 3d base.  Also, the Astros won't have a half season of negative performance in CF from Carlos Gomez.  This is an optimistic view of the future of the team's defense--but not unrealistic.