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At times, the temptation to make a well mixed gumbo out of just two ingredients -- correlation and causation -- is too much to resist. Pair it with the Biscuits of Comfortable Assumptions, and you have a nutritious meal. That brings us to the offensive decline of the 2020 Astros

The URL-clicker will recall that the Astros were the primary villains of the sign-stealing scandals that roiled baseball just before the ongoing pandemic came along. As MLB's official inquiry determined, the Astros undertook a scheme in which they used a replay monitor and center field camera trained on the catcher to decode the signs of the opposing battery. Then, as a humorously primitive finish, someone would bang on a trash can to signal the Houston batter when something other than a fastball was on the way. The advantages of such foreknowledge on the part of the hitter are so obvious that no further discussion is required.

Per MLB, the Astros used the scheme during the 2017 regular season and postseason, when they won the World Series, and partway into the 2018 season. That, however, may not be the definitive timeline. Even as late as the 2019 postseason, when the Astros won the pennant before falling to the Nationals in a taut seven-game World Series, whispers and sidelong glances abounded. 

To cite but one isolated instance, Jose Altuve of the Astros jumped on an Aroldis Chapman high-and-away slider and yanked it for a walk-off home run against the Yankees in Game 6 of the ALCS. As Altuve neared home plate, he rather intensely warned his teammates not to tear off his jersey in celebration. Subsequent events and related rumors gave rise to speculation that Altuve didn't want his shirt torn off because he was concealing a buzzer, which theoretically would be used to alert him when an offspeed pitch or breaking ball was on the way. Altuve initially explained his actions by saying he was modest and that his wife was upset with him the last time his jersey was ripped off. We'll leave it to the reader to apply the relevant smell tests to that alibi. 

As well, here's what Nationals catcher Kurt Suzuki said when Thomas Boswell of the Washington Post asked him whether the Astros were continuing to steal signs during the 2019 World Series

"Oh, yeah, no question. We could hear it from their dugout. We heard their whistling. What are you going to do?"

[...]

"We got a couple of big strikeouts when their crowd was so loud they couldn't hear," Suzuki said. "The whole thing was crazy. I got messed up on signs a couple of times, had to call time and take us out of rhythm. I kept thinking, 'We have to go to the field and work early on our signs in the World Series just to stop their cheating.' It's so stupid and so wrong."

At this point, it's worth remembering that the initial bombshell report by Ken Rosenthal and Evan Drellich of The Athletic that laid out the Astros' sign-stealing didn't drop until November of 2019 -- i.e., after the 2019 postseason. Maybe they were no longer flaying garbage receptacles for all to hear, but there's at least anecdotal cause to believe that the Astros' illegal sign-stealing extended beyond the parameters laid out in MLB's report. 

All of that brings us to the recently completed 2020 regular season. The Astros qualified for the expanded postseason, yes, but they did so despite a 29-31 record. More striking in light of all the above is the offensive declined suffered by Houston and its core hitters. Here's how things have gone for the Astros' offense over the last few seasons when it comes to some key indicators of quality, with their rank among AL teams in parentheses: 

Season/Statistic OPS Home Runs wOBA Chase rate SLG vs. fastballs

2017

.823 (1st)

238 (2nd)

.349 (1st)

29.2 (7th)

.524 (2nd)

2018

.754 (5th)

205 (7th)

.327 (5th)

29.0 (3rd)

.503 (4th)

2019

.848 (1st)

288 (3rd)

.355 (1st)

29.3 (5th)

.549 (2nd)

2020

.720 (9th)

69 (10th)

.311 (10th)

30.8% (9th)

.458 (10th)

The first two categories above are surely familiar. As for the rest: 

  • wOBA stands for weighted on-base average. It assigns proper value to every possible offensive event that happens while a batter is at the plate. Those proper valuations of singles, doubles, homers, walks, etc., distinguish wOBA from more traditional measures like AVG, OBP, and SLG (and OPS above). Also, for simplicity wOBA is scaled to look like OBP, which means that, say, .400 is elite and .290 is bad.
  • Chase rate is how often a player or team swings at a pitch outside the strike zone. 
  • SLG vs. fastballs is what a player or team slugged against four-seam fastballs. 

As you can see, it's a pretty clear pattern of decline across the board. The Astros this season were significantly worse when it comes to overall production, power output, selectivity, and success against fastballs. Given that the whole point of the scheme was to home in on fastballs by process of elimination, that last trend may be particularly telling. 

As for individual results of the Astros' best hitters, here are some potentially germane results: 

The schedule disparities of 2020 are also worth noting. Because of the COVID-19 pandemic teams this season played regional schedules -- 40 games against teams from their own division and 20 against teams from the corresponding division in the other league (e.g., AL West vs. NL West). This arrangement benefited the Astros, who wound up ranking 29th in terms of opponents' average winning percentage. In particular, they faced, generally speaking, much weaker pitching staffs than they have in recent years. Here's how their 2020 opponents fared in terms of ERA+, with 2020 MLB rank in parentheses: 

OpponentGames played2020 ERA+ (MLB rank)

Angels

10

89 (26th)

Athletics

10

111 (10th)

Mariners

10

85 (28th)

Rangers

10

91 (24th)

Diamondbacks

6

96 (18th)

Dodgers

4

141 (1st)

Giants

3

93 (22nd)

Padres

3

112 (9th)

Rockies

4

95 (20th)

ERA+ is a pitcher's or pitching staff's ERA adjusted to reflect home ballpark and league environment. It's scaled so that a mark of 100 is league average, and the higher the mark the better from the pitcher's standpoint. An ERA+ of 110 means that the pitcher's park- and league-adjusted ERA was 10 percent better than the league mean. Likewise, an ERA+ of 90 means that the pitcher's park- and league-adjusted ERA was 10 percent worse than the league mean. 

As made clear above, the Astros played most of their 2020 games against below-average pitching staffs. If you weight those ERA+ figures by games played against each opponent, then the Astros in 2020 on average faced an opponent with an ERA+ of 98. That means the Astros on average batted against subpar pitching staffs this season. Still and yet, Houston hitters mostly struggled to an extent that's far out of step with their recent history. 

None of this justifies flatly declaring that Houston's pre-2020 success at the plate is mostly attributable to nefarious practices. The 2020 season spanned just 60 games, and those 60 games were played under, to put it charitably, unconventional circumstances. However, that such sweeping decline has coincided with the presumed end of their sign-stealing is at the very least a notable curiosity. That's enough to make the narrative stick in some corners, even if it's not entirely fair. If nothing else, the Astros by now should be familiar with things that are, you know, not entirely fair.