How, in the chaotic world of the MLB postseason, do the Houston Astros keep doing this?
Six straight trips to the American League Championship Series. Four pennants. Even during an October when 100-win teams were dropping like flies, here Houston is again, having punched its ticket for the Fall Classic.
What's amazing about Houston's consistency over the past six years is that it's not the same group of players who began that run. From the infamous 2017 champion Astros, Jose Altuve, Alex Bregman, Yuli Gurriel, Justin Verlander and Lance McCullers Jr. are the only holdovers. That's a really good core, but still, the entire cast around them has turned over.
In this postseason format, randomness happens. Yes, we understand why teams win in the playoffs while they are doing it, usually because of some combination of a hot hitter or two and an airtight bullpen. It's predicting which team will get hot in advance that is so hard to do.
A month ago, who would have thought that the Philadelphia Phillies' bullpen would emerge as a dominant unit? Who had Harrison Bader and Rhys Hoskins among those leading the playoffs in homers?
However, not everything in this postseason has been surprising or flukey. For all those who want to defend the 100-win Los Angeles Dodgers, Atlanta Braves and New York Mets for their early dismissals, or decry the unfairness of the format, the one-word retort to all of this is simply: Astros.
Their current ALCS streak is remarkable. So how have they done it? We'll dive into that question, but we'll do so with the understanding that we aren't going to find a formula that fully explains Houston's run or perfectly predicts the outcomes of playoff series. If such formulas existed, the Tampa Bay Rays or Dodgers or Astros or one of the other really smart front offices in baseball, and their in-house think-tanks, would have found them.
What we can do is look at some general traits of these Astros and consider what kind of team traits have tended to be the most successful at playoff time. The intersections of these avenues of inquiry might suggest something, even if they fall short of creating the magic blueprint for playoff success.
A look back at the past decade
Let's call the period from 2013 to 2022 the Astros-Dodgers era, though Houston was still deeply in rebuild mode during the first couple of seasons of this window.
The Dodgers have won 931 regular-season games during that span, 73 more than any other team. They are followed by the New York Yankees, St. Louis Cardinals, Cleveland Guardians and Astros, who are all in the same neighborhood (832 to 858 wins). The Boston Red Sox and Rays have also topped 800 aggregate wins.
The Dodgers have advanced to the playoffs in all 10 seasons of that window; the Astros, Cardinals and Yankees sit at seven postseason appearances.
The Dodgers also lead in total playoff wins (53), but that's just one more than Houston (52), even though the Dodgers have had three more opportunities. L.A. is 53-47 in playoff games during the current era, while Houston is 52-34.
Boston ranks a distant third in playoff wins during this window (29) -- this is why we're calling it the Astros-Dodgers era. (Red Sox fans shouldn't complain though, as Boston is the only team during the window to win more than one title.)
Houston is 18 games over .500 in playoff games, the best differential over the past decade. No other team is particularly close.
Of course, winning in the playoffs isn't about winning individual games, but winning series. Houston dominates in that regard, as well. During that 10-year span, here are the teams with the best playoff series records, listed in order of most games over .500:
In any given season, a team can rise up and go on a title run, as did the Kansas City Royals in 2015, the Washington Nationals in 2019 and the Braves last season. But as long as we don't adhere to a binary definition of team success -- title or no title, and nothing else matters -- we can say that no team has paired regular-season dominance with postseason success over the past decade as well as the Astros.
What the Astros do
To circle in on some explanations for this success, we want to make some observations about what the Astros have done well during their run. Some of these things have remained constant even as the roster has turned over.
Houston has generally fielded a top-10 offense, with park-adjusted scoring totals ranking eighth or better in each full season since 2015. But during the current era, the reason Astros' offenses have stood out is lineups that balance different skill sets even as three-true-outcomes baseball has proliferated across the majors.
To wit: Houston has ranked in the top five a couple of times in walk rate but generally has been more upper-middle class in this trait than elite. You can make the same observation about homers; the long ball has played a part, but it has never fully explained the Houston offense. The most persistent trait in Houston offenses over the past 10 years has been their ability to put the bat on the ball and control the strike zone.
Astros hitters have finished first or second in the majors in strikeout rate in each season since 2017. This has held true even as the names in the lineup have changed. Also, in terms of strikeout rate minus walk rate -- a measure of strike zone command -- the Astros have also ranked first or second over the six seasons of their ALCS run, save for a fourth-place finish in the shortened 2020 season.
Season in, season out, the Astros' power numbers have ebbed and flowed, but they always control the strike zone and they always hit for contact.
One other key observation about Houston's position players: They catch the ball.
According to Fangraphs' DEF metric, which combines multiple defensive evaluation systems (most notably, fielding runs and positional adjustment), Houston has ranked sixth or better in each season since 2016, except for a slump in 2020. It's been third in each of the past two seasons.
On the pitching side, there has been more inconsistency, with park-adjusted runs allowed rankings that have ranged from first (2018 and 2022) to 14th (2020). When the Astros are playing their best baseball, their pitchers have tended to mirror the strengths of their hitters. They have ranked first or second in strikeout rate and strikeout-minus-walk rate in those seasons.
As with the offense, the Astros' homers allowed figures have gone up and down. In 2019, Houston pitchers ranked 22nd in homer rate allowed, and they were 11th last season. This season, they were second -- their best ranking during the current era.
In terms of units, Houston's rotations have ranked in the top five in quality start percentage in four of the past five years, and eighth in the other year. The bullpen performances have ping-ponged, though the Astros have generally been able to pull it together during the playoffs. Houston ranked 10th or better in bullpen fWAR in each season back to 2017. Situationally, the Astros ranked fourth in saves-plus-hold percentage in 2019 and second this season. In between, they were 25th and 26th.
To sum it all up: When the Astros are at their best, they dominate the strike zone at the plate and make contact with sometimes-elite power. They catch the ball, and they induce swing-and-misses on the mound.
How it all plays out
In order to apply our observations about the Astros to postseason success, we calculated a whole bunch of won-lost records. This simple method is most easily described by example:
Over the past decade -- and considering series of all lengths, including winner-take-all wild-card contests -- the teams with the better regular-season winning percentage have gone 52-39 in series (six series have matched teams with the same win total). That's a .571 percentage in favor of those with the win edge. We analyzed those 97 series the same way using many different kinds of criteria.
Let's run through the highlights while paying special attention to the Astros.
Run differential
One of the most important immediate takeaways is that run differential is a much better predictor of postseason series success than basic winning percentage. Teams with the differential edge have gone 57-40 (.588).
This has been less true for the Astros, who have had a better differential than their opponent in 12 of 18 series. They've won just eight of those 12, but they've also won five series in which they had a worse run differential than their opponents. This year's Yankees are the fifth Astros victim in this regard.
Run scoring
Teams with better regular-season home run differentials (homers hit vs. homers allowed) have gone 51-46 (.526), so there is predictive value in that measure. However, you'd be better off just using park-adjusted scoring. The higher-scoring offenses have gone 58-39 (.598), making it an even better predictor of playoff series wins than run differential.
Overall, teams lose a lot more offense than pitching when comparing their regular-season and playoff scoring rates. Over the past decade, the average playoff team has lost 0.81 runs per game over its regular-season figure. However, runs allowed go up by just 0.08 runs even with the heightened competition. Games are closer and lower-scoring. We know this.
However, teams that are able to best retain a semblance of the regular-season scoring rate fare better at playoff time. Run prevention is also a solid predictor but not to the same scale. Teams with the better regular-season runs allowed total have gone 54-43 (.557) -- very good, but not as predictive as the offensive figures.
The Astros have gone 9-3 in playoff series in which they played teams they outscored during the regular season. The exceptions were the World Series losses in 2019 and 2021 (Nationals and Braves, respectively) and the 2015 ALDS loss to Kansas City.
Of course, Houston has also gone 4-2 since 2013 in series where it has played teams that scored at a higher rate than it did. Three of those wins: Yankees in the 2015 wild-card game, Yankees in the 2019 ALCS and Yankees in the 2022 ALCS.
Strike zone command
Teams have gone 53-44 in series when owning an edge in hitter strikeout rate. The Astros have had the edge in 15 of their 18 series during this time and won 11 of those series. Even more predictive overall has been strikeout-minus-walk rate, our proxy for hitter strike zone command. Teams with the edge in this area have gone 55-42 (.546).
For the Astros, the success rates are the same either way. They've held the edge in strikeout-minus-walk rate in 15 of 18 series and won 11 of those series.
Defense
Clubs with better regular-season DEF totals at FanGraphs have gone 51-46 (.526). It adds some predictive value, but the relatively lower success rate reflects that some teams (like this year's Phillies) are built differently.
This factor has been more important for the Astros, however, as Houston has gone 12-3 in series when owning a defensive edge on its opponent. Two of the losses came in the World Series (2019 and 2021).
Strikeout pitching
Teams with an edge in overall strikeout rate have gone 52-45. Meanwhile, they've gone 49-48 in terms of strikeout-minus-walk rate, which we usually think of as a good measure of regular-season pitching dominance. In the playoffs, pure K-rate has been more telling.
The Astros have had a K-rate edge in 12 of their 18 series, winning eight of those. In terms of strikeout-minus-walk rate, they've gone 6-3 when having the advantage.
ASTRO blend
We tried this in about 1,000 different ways, but we found one simple combination of metrics that worked fairly well to suggest what has worked for the Astros at playoff time. Let's call this metric ASTRO.
The categories used in ASTRO:
Offensive strikeout-minus-walk rate
Defense
Pitching strikeout rate
That's it. Simple, but it's our most predictive metric yet.
Teams with an edge in ASTRO have gone 59-38 (.608) over the past decade. The Astros have had the edge in ASTRO in 15 of their 18 playoff series during the current era -- and they've won 12 of those series. The exceptions: the 2018 ALCS against Boston, the 2019 World Series against Washington and the 2021 World Series against Atlanta.
These traits -- strike-zone command at the plate, defense, missing bats on the mound -- have been among the most prevalent traits of the Astros in recent years, and they've served Houston well in the playoffs.
We know this is not a secret sauce, because while ASTRO performs well in the aggregate and for Houston, it certainly doesn't work for everyone. Still, you want to know why the Astros keep hanging around at playoff time even while behemoths around them fall by the wayside?
Randomness is the biggest reason. But they are really good, too, and they are really good in ways that seem to maximize their chances to stave off the inevitable chaos of the postseason, at least for a while. You don't need metrics to realize this. You only have to turn on a ballgame late in October.