Astros Update: Run Prevention

Run prevention is the combination of team defense and pitching. In a practical sense, you can’t separate the two components of run prevention. For instance, Framber Valdez is very good at preventing runs with the Astros’ infield defense behind him. However, he would not be nearly as good if he played with a poor infield that leaked ground balls like a sieve. Most Astros’ pitchers have a Fielding Independent Pitching (FIP) metric higher than the player’s Earned Run Average (ERA), largely due to the Astros’ above-average defense.

Team Defense

This early in the season, the defensive metrics should be taken with a grain of salt. Typically defensive metrics require a lengthy period or sample size to stabilize. With just a little over one month into the season, the results and team rankings can change significantly in a matter of a week’s time. The results show us how a fielder has performed over a relatively brief window, but may not tell us much about the defense over the long term.

The Fielding Bible, which is based on Defensive Runs Saved (DRS), publishes team defense rankings. The 2023 ranking so far are shown below (credit: Fielding Bible).

The Astros are ranked 6th best with +10 defensive runs saved above average. In 2022 the Astros ended the season with the 4th best DRS. Because the shift accounted for a large part of the Astros’ runs saved in 2022, it’s possible that the MLB shift limitation has cost the team some of its DRS ranking in 2023.

The Astros’ defense has been negative at catcher, 1b, LF, and RF, but this is more than offset by +3 at each of 3b, SS, and 2b, and +4 in CF. The limited shift allowed by the rules and outfielder positioning has added +3 and +1 (respectively) to the DRS team total.

An alternative defensive metric is Outs Above Average (OAA), a range-based Statcast metric. The Astros are tied with the Mets and Rays for 6th best with +5 outs above average. While the metric values may be different, the Astros team ranking is basically the same as for DRS.

The positional rankings for OAA and DRS generally are similar. However, OAA and DRS disagree on the Astros’ defense at shortstop. OAA rates the Astros shortstop defense as somewhat negative (-1), but DRS ranks the Astros shortstop as a positive (+3). DRS rates the Astros left field defense as somewhat negative (-1), but OAA rates LF as average (0).

Right field defense is a surprise—but not in a good way. Kyle Tucker was a gold glove winner and the best defensive right fielder. So far, both OAA (-1) and DRS (-4) rate the Astros’ RF defense as negative. The DRS ranking is 26th, and the OAA ranking is 18th. I have noticed a few questionable plays in RF, and this may be just a case of blowing up a few miscues in a small sample size. I also wonder if the shift restriction, specifically prohibiting the 2d base “rover,” has hurt Tucker. Notably, a few more bloopers than usual seem to be falling into shallow RF.

Both McCormick and Meyers deserve credit for making CF a team defensive strength. Similarly, Mauricio Dubon, who previously was a part-time player at various positions, has turned 2b into a defensive strength.

After the season's first month, the Astros’ defense continues to provide high-quality run prevention behind the pitching staff.

Team Pitching

And briefly, let’s update the team pitching ranks. For simplicity, we can look at the traditional stat, ERA, and the advanced stat, SIERA. The Astros' starting pitchers are sixth in ERA (3..42) and sixth in SIERA (4.03). The Astros’ bullpen is fifth in ERA (2.97) and 2d in SIERA (3.42). This is a significant improvement for the bullpen, which was previously ranked 14th by ERA when I last wrote on this subject (10 days ago).

For the immediate future, the biggest immediate question surrounds the recent placement of two starting pitchers (Urquidy and Garcia) on the Injured List. With Lance McCullers Jr. already on the IL, the Astros starting pitching depth will be tested. At this point, we don’t know enough about the severity of these injuries to predict the impact.

The predicament has raised the question, both in the local media and on MLB-Network, as to whether the Astros should have acquired starting pitcher depth in the off-season. Chandler Rome reminded his Twitter followers that Dusty Baker previously indicated that he wanted to acquire another pitcher, but the team’s lack of a GM at the time prevented him from pursuing it. My article in December 2022 (“Will the Astros Need to Sign Another Pitcher?”) concluded that the Astros starting pitching depth was inadequate and argued that the Astros should sign a veteran pitcher, either a middle-tier starter or a swing starter.

Currently, beyond Brian Bielak, no starting pitcher in AAA is the obvious choice to be promoted to the major league rotation. An argument could be made for 28-year-old J.P. France, or one could go with “roll the dice and bet on Forrest Whitley’s stuff.” With Bielak already on the roster and a Thursday off day, the Astros may be able to avoid adding another starting pitcher until May 9. We don’t know if Urquidy or Garcia will require more than 15 days before returning to the rotation. If they are out of the rotation for longer, the starting pitching depth becomes more problematic.