Astros Defense and Run Prevention

The recent struggles of Framber Valdez, Cristian Javier, and Hunter Brown have received a lot of attention. And for good reason: it is difficult to see how the Astros can win a tight playoff race if the team can’t figure out how to reverse the recent rotation problems. The struggles include hard contact, unusually short outings (which will ultimately hurt the bullpen), and erratic command of pitches.

While it’s important to diagnose and fix these pitchers’ individual issues, poor pitching results are a team issue that includes run prevention. Run prevention is a combination of team defense and pitching. The results of poor defense will show up on the pitchers’ side of the ledger. The sloppy play in the field during the recent series with the Mariners drove home the impact of defensive lapses. However, the deteriorating defensive performance has been underway for a couple of months.

At the same time that starting pitcher performance has fallen apart, the defense has also suffered serious deterioration. I’m not saying that the defense is totally responsible for the decline in starting pitching performance, but it is a contributor to the problem.

As I’ve written previously, Framber Valdez and Hunter Brown have issues with allowing hard contact. Among qualified starters in the majors, Valdez is No. 1 and Hunter Brown is No. 5 in high exit velocity. I have suggested that for these two pitchers, declining ground ball rates could affect their ability to manage hard contact. However, it’s also important to note that exceptional defense will help suppress the run-scoring that may be associated with high exit velocity. So, declining defensive performance is not a good combination with higher exit velocity.

As a team, the Astros’ rotation is No. 5 in high exit velocity, No. 1 in number of barrels allowed, and No. 9 in hard hit percent.

For my examination of the Astros’ team defense, I will use the Fielding Bible’s Defensive Runs Saved (DRS). The Astros are currently ranked 19th in team defense. Last year, the Astros were an exceptional defensive team and were ranked 4th in team defense. The Astros’ defensive ranking was 13th at the beginning of July but has declined to the current 19th ranking.

On July 1, the Astros’ rotation had the 3d lowest ERA (3.60), but today the Astros’ rotation is ranked 8th in ERA (4.01). One way of comparing the recent direction of the Astros’ defense with the direction of the Astros’ pitching is to compare ERA, FIP, and DRS for intervals before and after July 1.

Thru July 1

Astros 3.60 ERA (Rank 3d) 4.17 FIP -0.56 E-F +7 DRS

July 2 - Aug. 22

Astros 4.84 ERA (Rank 21st) 4.64 FIP +0.19 E-F -3 DRS

• Comparing E-F (ERA minus FIP) is useful because it is relevant to both defense impact and pitcher regression. Fielding Independent Pitching (FIP), as the name implies, excludes the impact of defense. Therefore, the margin of FIP over ERA should partly reflect defensive runs above average. In addition, we normally expect ERA to regress in the direction of FIP.
• Both ERA and FIP increased for the period after July 1. But the margin between ERA and FIP changed the most. The Astros went from No. 1 in FIP margin over ERA before July 1 to the 8th highest margin of ERA over FIP since that date. Early in the season, the Astros rotation was very good at keeping the ERA below FIP, but in the more recent interval, ERA is above FIP by a noticeable margin.
• In the recent interval after July 1, the Astros' defense has contributed negative defensive runs saved.
• While the decline in Astros’ defense has contributed to the change in E-F during the recent interval, the fact that ERA exceeded FIP during that period may suggest that we should expect downward regression.

Based on the 2022 defensive performance, we know that the current Astros team is capable of playing exceptional defense. If the Astros can focus on defensive execution over the remaining games, this will make the job of improving the rotation’s results easier.

And Now...and Update on the Playoff Odds

As I mentioned in previous articles, the Fangraphs playoff odds are fairly volatile as we head into the final quarter of the season. In particular, the odds of winning the AL West flip back and forth between the Astros and Rangers, depending on each day’s game results. Meanwhile, the Mariners’ August win percentage has strongly increased their playoff odds.

After the Monday games, the Astros moved into the lead for top odds of winning the division. the Division odds and Playoff odds are shown below.

Astros Division Odds 44.8% Playoff Odds 84.0%

Rangers Division Odds 33.0% Playoff Odds 77.6%

Mariners Division Odds 22.3% Playoff Odds 65.8%

The AL West division odds are tighter than they look at first glance. The Fangraphs model projects a final W/L record with the Astros 0.7 wins ahead of the Rangers and 2 wins ahead of Seattle. And the order of these teams can flip quickly with each game-to-game result. The remaining games are a small enough sample that game-by-game results cause a significant change in odds.

Another notable point: the Fangraphs model expects all three AL West teams to make the playoffs. The Playoff Odds for all three teams are greater than 60%.