Quick Thoughts: Astros Face Final 15 Games

The final 15 games of the season are shaping up as the most exciting finale to the season that Astros fans have experienced in the last six years. Why? In previous seasons (excluding 2020), the Astros had the division championship sewed up at this stage. In 2023 the Astros face a dog fight for the AL West championship and, alternatively, wild card position.

I will provide an update on playoff odds at the end of this article. But in the meantime, I submit for your approval, some relevant Astros’ facts.

Parsing Splits for the Astros’ Offense

I like perusing the hitting splits page at Baseball-Reference.com. The split statistics can be quite relevant at this time of year. For one thing, it’s almost a full season of data. And, secondly, the splits may tell us what to expect from game to game over the final two weeks.

• The Astros’ offense likes facing LHPs. On average, MLB teams are 3% better at hitting left handed pitchers than right handed pitchers (OPS+ 102 vs. LHP and 99 vs. RHP). By comparison, the Astros feast on LHPs. The Astros’ batters are 19% better than the league at hitting LHPs (OPS+119). The Astros’ batters are 17% better at hitting LHPs than RHPs.
• The Astros’ offense is much worse at home. You probably knew that. But the split is surprisingly wide. The Astros’ hitters are 9% worse at home than their overall OPS. (tOPS+ 91) The Astros’ hitters are 25% better on the road than at home (sOPS+ 121 road and 96 at home. By comparison, the average MLB team is 7% better at home than on the road. (tOPS+ 103 at home and 96 on the road.)
• The Astros’ weakest spots on offense have been 1b and DH. This is based on league average OPS+ for those positions. The Astros’ 1b has been 25% worse, and the DH is 3% worse, than MLB average OPS+ for those positions. The Astros’ Catcher OPS+ is only 1% worse than the MLB average for the position. Although it’s technically not a position, Astros’ pinch-hitters are 21% worse than league average for PHs. (The bench hasn’t been great.) The Astros’ remaining positions are considerably better than league average.
• The Astros’ hitters are really good when it counts. It’s not unusual for batters to hit better in high leverage situations. The average MLB offense is about 4% better in high leverage situations. But the Astros’ batters excel in those situation: the Astros increase their OPS by 9% in high leverage and they are 14% better than league average for high leverage situations. The average MLB team increases its OPS by 10% with runners in scoring position (RISP). The Astros hitters increase their OPS+ by 21 percent with RISP, and they are 22% better than the league average with RISP. The Astros’ OPS+ is 5% better than the league average for late and close games.
• The Astros’ hitters are confounded by ground ball pitchers. On average, MLB teams’ OPS+ is 6% worse against ground ball pitchers (lower third of pitchers in Fly-GB rate). But the Astros are much worse versus ground ball pitchers. The Astros’ batters are 16% worse against ground ball pitchers. (Wondering why the Astros lost the first two games of the recent Oakland A’s series? Perhaps this stat partially explains the result.) The Astros’ best split is against pitchers who are evenly balanced between ground balls and fly balls (OPS+ of 116).

It’s Not Worth Fretting Over Lineup Choices At This Point In The Season

It’s no secret that daily lineup decisions have been a source of contention among Astros’ fans. I sometimes agree with those concerns. But now that we are in the final three weeks of the season, some fans are exasperated because they believe controversial lineup choices over this finale period will ruin the Astros’ playoff chances. That is understandable to some extent. But, given the amount of time left in the season, it’s unlikely that the lineup decisions will materially affect the Astros’ playoff chances.

As a test, I examined the Fangraphs Depth Chart for “Rest of Season” (ROS) WAR projected for each player, which is utilized in the Fangraphs’ Playoff Odd Model. The playing time decisions for Yainer Diaz and Chas McCormick are the most discussed lineup issues (although they are not the only lineup controversies). Using ROS WAR, I considered whether Diaz vs. Maldonado and McCormick vs. Dubon playing time choices could even change the Astros’ projected win total by 1 win. If Diaz replaced all of the projected Maldonado starts, the impact is less than two-tenths of a win. If McCormick replaced all of the projected Dubon starts, the impact is even less, at three-one hundredths of a win. My general conclusion is that the controversial lineup choices are likely to have a minimal impact on the Astros’ playoff chances.

With only 15 days left, random variation overwhelms these individual discrete decisions. If we could reliably predict Wins Probability Added (WPA) for each player, we might be able to say more, but WPA is largely unpredictable—and that is doubly true if we try to predict a player’s WPA over a 15 day period, when factors like sequencing and RISP are largely random.

Don’t get wrong. I would like to see McCormick and Diaz get a lot of playing time in the remainder of the season. And I’m not saying “ignore the lineup.” But my advice is, don’t let the lineup choices drive you to distraction. Maybe it’s helpful to your enjoyment of the games to know that the likely impact is very small.

I was reminded of the fact that “baseball has a lot more randomness and a lot less variation in skill between a player and their backup” by Ben Clemens’ article analyzing the Rangers’ loss of Scherzer and it’s impact on the playoffs. His article points out that the loss of Scherzer is not projected to change the Rangers’ final Win%, and only has a minor impact on the playoff odds. In the example discussed by Clemens, one day of playoff losses by competing teams has triple the impact on the Rangers’ playoff odds of “replacing a star player with a journeyman” for the rest of the season.

Playoff Odds for Astros

Now to the update from the Fangraphs Playoff Odds. The Astros continue to be a considerable favorite to win the division. But the Rangers’ recent wins have narrowed the divisional odds between the Rangers and Mariners, and obviously improved the Rangers’ playoff odds.

(Projected Wins, Division Odds, Make Playoffs)

Astros 92 Wins, 63.5% Division Odds, 97% Playoff Odds

Mariners 89 Wins, 19.0% Division Odds, 81% Playoff Odds

Rangers 90 Wins, 17.5% Division Odds, 88% Playoff Odds