The Astros are heading back to the postseason, and it’s been incredible in a variety of different ways. It’s the first time the team will be playing in October in back-to-back seasons since 2004 and 2005. But more than that, they’re the first reigning champions to win 100 games since the 1990 Athletics, and if they can take three of four games from the worst team in baseball, they’ll set a franchise-best mark in wins.
A big part of that success is from their pitching, which has been unbelievable in a number of ways. To give just a few examples: the pitching staff has recorded the second-best Wins Above Replacement total for a staff in history, according to Fangraphs, trailing last year’s Indians staff by just 2.4 Wins. If they can limit the Orioles to under 27 runs in four games, they’ll set a record for fewest runs allowed by an AL team in the DH Era. They’ve already set the MLB record for most strikeouts by a staff with 1652 (again, with four more games against an abysmal, whiff-heavy Orioles offense to pad that total), 38 ahead of last year’s Indians and 64 ahead of this year’s second place team.
On an individual level, four of the team’s five starters set personal-bests in strikeouts (and Keuchel, in spite of his struggles, still posted his second-highest K total, behind just his Cy Young season). Justin Verlander and Gerrit Cole have gotten most of the attention as they vie for the league strikeout lead, but even Lance McCullers and Charlie Morton are getting in on the fun. It’s quite a diverse group, with the 24-year-old former top prospect still growing into his role, the prime-aged former top pick finally having what looks to be his big breakout year, and a pair of mid-thirties pitchers who came to the team as a Cooperstown-bound ace and a reclamation project. And all of them have struck out more batters than ever since coming to Houston.
In light of the success of so many members of the staff, it’s worth taking a look at one of the brains behind it. Brent Strom is currently the oldest pitching coach in the majors, turning 70 in just under three weeks. He pitched in the majors for a few years, then became the second person in history to get Tommy John surgery. Unlike the surgery’s namesake, who threw fourteen more years afterwards, Strom never made it back to the majors. He mostly served in some minor league coaching roles after retiring, with a pair of stints as a Major League pitching coach in Houston (1996), then Kansas City (2000-2001). He had been out of the game for a few years when Jeff Lunhow offered him the chance to help develop minor league pitchers for the Cardinals, then Lunhow came knocking again in 2014 as the General Manager of the Astros. The team’s transformation under Strom since then has been remarkable.
The year before Strom arrived, Houston ranked 29th in the league in strikeout rate at just 17.0% of batters faced. Every year since then, they’ve steadily improved by a few points and climbed a few spots in the rankings each year. They’ve similarly improved in walk rate as well, although it hasn’t been as neat or steady.
Astros Strikeout and Walk Rate, 2013-2018
But what might even more dramatic than the increased lack of contact is the type of contact that opposing batters do make when they aren’t whiffing. Fangraph’s batted ball data includes stats called Soft%, Med%, and Hard%, which as you might expect break down how well hit balls are. For the few years prior to Strom’s arrival, Astros staffs tended to rate toward the middle of the pack, peaking in the low-single digits but generally falling somewhere between the mid-teens to low-twenties in the league-wide rankings.
In the five years since Strom’s arrival, the team has never ranked worse than seventh place in the majors, and has finished in the top two three times. This generally hasn’t come at the expense of medium-hit balls, as they’ve continued to rank decently there as well.
Astros Pitchers’ Soft and Medium Contact, 2013-2018
There isn’t some uniform secret fueling this; it’s not like every pitcher who winds up in Houston suddenly picks up a new cutter or throws three miles and hour faster. Players have praised his strategizing for individual pitchers, and that seems to be the case. Sometimes it’s more fastball (Verlander is throwing over 60% fastballs this year, the first time he’s done so since 2009), sometimes it’s paring down pitch selection to focus just on what works (Cole has largely abandoned his once-prominent sinker to throw more cutters), sometimes it’s cutting down on walks and getting more fly balls (Morton’s change after a rediscovery of his fastball in Philadelphia).
But while there’s no uniform change in how pitchers change under Strom, there is a definite goal in mind while making these tweaks. Under Strom, Astros pitchers have become uniformly better at getting batters to chase pitches out of the zone and miss. They still swing at things inside the zone at about the same rate (from 2013 to this year, opposing batters have swung at pitches in the strike zone between 64.2 and 66.2% of the time, ranking between 23rd and 30th in the league overall), and as they’ve obtained pitchers with better stuff, they’ve started to get more swings-and-misses in the zone. But it’s the outside-the-zone stuff that seems to show Strom’s philosophy in how to approach an at-bat.
Astros Pitchers’ Swing and Contact Rates, 2013-2018
That sort of staff-wide improvement is what leads me to think this is a top-down push. Before he arrived, batters facing Astros pitching generally laid off bad pitches and when they did swing, it was on something they had a good chance of putting in play. But by 2015, the Astros were a regular top-ten staff at getting batters to chase and at getting them to miss when they did, and they’ve been a top-two team in lowest contact rate outside of the zone for three years running now.
That type of game plan helps explain how the team racks up its Ks and limits runs. Getting batters to chase bad stuff makes it harder for them to do anything with it in the first place, and a 12-point drop in contact at pitches outside of the zone means a lot of extra strikes to work with. Getting pitchers who are so good at missing bats even in the zone helps as well, which is how you get a historic season like 2018, but overall, that’s a lot of extra strikes to work with, which helps keep you ahead in the count, picking up outs, killing rallies, and limiting runs.
Overall, it’s a fascinating approach that’s paid huge dividends, especially as the team has acquired more and more pitching talent and as the league has moved more and more towards strikeouts. Strom’s plan has set the Astros up well for the rest of this season, and that the philosophy guiding this year’s staff has been carried over so easily to the newer members of the team as they arrive gives me a good deal of confidence in any pitchers who join the team in this coming offseason and beyond.