World Series 2023: Diamondbacks rookie Brandon Pfaadt is the latest Brent Strom pupil to thrive on the leading edge of pitching

With the help of the legendary pitching coach, Arizona's Game 3 starter reworked his approach in time to dominate this postseason

PHOENIX — If someone asks you to explain what changed for the Arizona Diamondbacks between the regular season and October, how the team found a new gear to power through the postseason and reach the World Series, one of the simplest answers you can provide is “Brandon Pfaadt.” That’s a silent P, pronounced like “fought.”

A longer answer might go something like, “Pfaadt fought through acute early struggles in the majors, returning to the minors on multiple occasions, and eventually made changes that clicked just in time to make him a formidable No. 3 starting pitcher, something few contenders could match.”

Here, let Diamondbacks starter Merrill Kelly say it.

“I mean, he's arguably been our best starting pitcher,” Kelly said before definitively taking that title for himself in World Series Game 2. “In that Phillies series, obviously me and [Zac] Gallen scuffled early. And the fact that Brandon was able to put the brakes on the skid when we went back home just kind of shows you the difference between where he was in the beginning of the season compared to where he is now.”

The rookie right-hander, who started crucial Arizona victories in Games 3 and 7 of the NLCS, will be on the mound Monday for World Series Game 3, standing in stark juxtaposition with Texas Rangers starter Max Scherzer, the future Hall of Famer who has been making high-pressure postseason starts since Pfaadt was 11 years old. This intergenerational matchup strikes not only at the differences in team construction in this Fall Classic but also at a larger truth about pitching in the majors: You’re either ahead of the curve or falling behind it. And time doesn’t defer to Baseball-Reference pages.

'We go to plan B'

Diamondbacks pitching coach Brent Strom turned 75 years old earlier this month, one day before Pfaadt turned 25. A grizzled baseball lifer who counts both Sandy Koufax and a slew of data-driven, contemporary pitching analysts and researchers as close friends, Strom is best known for his time as the Houston Astros’ pitching coach, during which his trend-setting teachings revitalized Justin Verlander, supercharged Gerrit Cole and guided a menagerie of less proven arms to success.

He left the Astros after 2021, in the middle of their streak of runs to at least the ALCS — seven and counting — in part because he was tiring of maintaining greatness instead of discovering it. Initially, Strom simply retired. But shortly thereafter, the Diamondbacks came calling. A new challenge (and a geographic match close to his Tucson home) lured him back.

Acclaimed pitching coaches tend to have their reputations boiled down to one neat trick, and many of them fade away when that trick gets overwhelmed by the tide of the game’s natural competitive reaction. Strom’s gospel in Houston revolved around the power of the high four-seam fastball, the “rising” action that induced whiffs and neutralized increasingly homer-focused swings. He still preaches the power of that pitch in Arizona, but his impact and his longevity stem from the constant quest to understand and apply the most current research on how to beat the world’s best hitters.

Pfaadt was exactly the type of challenge Strom sought when he joined Arizona, fresh off the team’s 110-loss 2021 season. A fifth-round pick in the abbreviated 2020 draft, Pfaadt rocketed through the minors with obvious major-league-caliber stuff. Heading into this season, he was a heralded, if divisive, prospect. FanGraphs ranked him the 16th-best prospect in baseball; Baseball Prospectus ranked him 83rd.

His first taste — first several tastes, really — of the majors did not go well. Across Pfaadt’s first six starts, he amassed a 9.82 ERA and got demoted twice. With each trip to the minors, Strom and the Diamondbacks gave Pfaadt assignments, tweaks to adapt his unquestionably sharp stuff — featuring a 94 mph fastball, a frisbee-style sweeper and a changeup — to get big-league hitters out.

“I've always gone with the idea of trial and error,” Strom said, noting that his “whole joy is seeing these guys succeed.” “If I try it and it doesn't work, I'm not offended. We go to plan B.”

With the help of pitching coach Brent Strom (right), rookie starter Brandon Pfaadt has become a formidable No. 3 for the Diamondbacks. (Photo by Elsa/Getty Images)
With the help of pitching coach Brent Strom (right), rookie starter Brandon Pfaadt has become a formidable No. 3 for the Diamondbacks. (Photo by Elsa/Getty Images)

'From there on, we probably won't go back'

Between Pfaadt’s last trip to the minors and his return to the Arizona rotation in late July, Strom devised a change to alter how hitters saw the ball out of Pfaadt’s hand. The immediately apparent physical tweak was a move to the extreme first-base side of the rubber.

“I think the final adjustment, which was the most critical adjustment, was moving him on the rubber, which changed the shape of his pitches coming into home plate. Since that time, he's really taken off,” D-backs manager Torey Lovullo said this month. “But once again, that's our architect in Brent Strom getting information [and] a player trusting it.”

After returning from the minors in late July, Pfaadt compiled a 4.22 ERA in 70 1/3 innings and showed flashes of excellence in two scoreless September starts. In the postseason, he has started four times — all Arizona wins — and posted a 2.70 ERA in 16 2/3 innings with 22 strikeouts, three walks and, most importantly, only two homers.

“I mean, you got to trust him,” Pfaadt said of Strom. “He's been there. He's very knowledgeable in what he thinks and what he says, and at the end of the day, it's almost like trial and error. And I gave it a run, and it worked out, and from there on, we probably won't go back.”

In addition to the shift on the rubber, Pfaadt sprinkled in more sinkers that play up the run — or arm-side movement — inherent on his fastballs and amped up the use of his sweeping slider, reducing the reliance on the four-seam fastball that had been getting crushed. As Strom explains it, the ball now comes out of Pfaadt’s hand looking like a strike far more often, which puts pressure on hitters to swing, even at pitches that often dart or dive out of the zone, out of danger.

“He's a low-three-quarter-slot guy that has a lot of running fastballs,” Strom said. “So basically, I kind of liken it to a golfer who has a slice, and so they aim to the left side of the fairway to play the slice, and they end up in the middle.”

The value of coaching, of an intermediary such as Strom, is that he speaks to a young pitcher with the credibility of an icon who just texted Sandy Koufax as well as the contemporary knowledge of a wonk who is deeply engaged with the work of analyst Perry Husband, also a friend. Husband’s concept of “effective velocity” was behind Pfaadt’s adjustments.

Effective velocity is one way of quantifying how hitters’ eyes and brains perceive pitch sequencing — a high and inside fastball like Strom is famous for encouraging has created swings adapted to get ahead of the ball and slightly under it for power. Even if the pitch is actually going 94 mph, it might have the hitter moving and thinking at 97 mph. If the next pitch is an 84 mph sweeper that lands down and away after initially appearing to follow the fastball’s tunnel up and in, the combination makes the disparity for a hitter effectively much greater than the 10 mph difference.

'Both fastballs have felt better than ever'

Regardless of the actual statistical maneuvering behind it, the concept dovetails with the thinking going around major-league front offices as pitchers adjust to hitters … who themselves have adjusted to the high-fastball-centric strategies that Strom popularized in Houston.

At his best, Pfaadt uses the Strom-imparted philosophy to queue up combos with which he flummoxes hitters with pitches that start out looking the same, then veer off in different directions at different speeds. From his new angle on the first-base side, that has been especially apparent in how he pairs his breaking ball — categorized as a sweeper but a particularly hard and tight version of it that nudges toward slider territory — with fastballs that could be more vulnerable without their swerving counterpart.

Watch how he got ahead of Phillies star Trea Turner in NLCS Game 7. Pfaadt opened with an 87 mph sweeping slider that initially looked like it might be a four-seam that landed middle-up.

Brandon Pfaadt throws a sweeper to Trea Turner in NLCS Game 7.
Brandon Pfaadt throws a sweeper to Trea Turner in NLCS Game 7.

Up 0-1, Pfaadt went to the sinker, which again Turner might’ve mistaken for a middle-up four-seam. It dove out of the zone inside.

Brandon Pfaadt throws a sinker in NLCS Game 7.
Brandon Pfaadt throws a sinker in NLCS Game 7.

Even if the full rationale never needed to be detailed for the young pitcher, these days Pfaadt can feel the benefits.

“I think both fastballs have felt better than ever since the end of the year and compared to early on,” he said ahead of the World Series, “and I think that's opening up every offspeed, and it's helping out those pitches when we need to pull those out of our back pocket and show those as well.”

Soaring under the brightest lights baseball has to offer, Pfaadt will enter both his first World Series and the rest of his career with a more defined vision of his own strengths and a more confident approach to making the adjustments that will inevitably be necessary if he’s going to replicate this type of success in 2024 and beyond. Strom will be watching — or perhaps listening anxiously from the depth of the dugout — and formulating the next message for Pfaadt and for pupils to come.

“And really, it's not so much the information — it's the presentation that's the most important thing,” Strom said. “You have to gain the pitchers' trust that you have their best interests at heart and why this may work.”