How Tanner Houck is putting it all together for the Red Sox

After beginning spring training as Boston's No. 5 starter, Houck has leveled up both his arsenal and his command this season

Every baseball season brings a new wave of surprise breakout players, those who surge from the lower levels of the depth chart to full-blown stardom in a relative blink. This year, amid a first half filled with eye-popping and unexpected pitching performances across the league, Red Sox right-hander Tanner Houck — the current American League ERA leader and tops in fWAR among qualified starting pitchers — stands out as a particularly remarkable ascent.

After trading Chris Sale in December and signing Lucas Giolito in January, the Red Sox opened spring training with four spots in their projected rotation seemingly secure. Giolito was brought in to solidify the top half with his track record of durability and upside beyond that. Brayan Bello, who signed an extension before Opening Day, was Boston’s innings leader in 2023. Kutter Crawford and Nick Pivetta each took big steps forward as rotation members last year as well and seemed like safe bets to repeat in those roles.

While Houck also finished 2023 in the Red Sox rotation, he had much more to prove entering 2024. It had been a challenging stretch for the right-hander, whose 2022 ended early due to back surgery before his 2023 was derailed when he was hit in the face by a comebacker, a scary injury that cost him two months. Navigating two wildly different yet significant rehabs made it difficult for Houck to find his groove, and he finished last season with 5.01 ERA across 21 starts, ranked 54th among 65 AL starting pitchers with at least 100 innings pitched.

As a result, at the outset of camp this year, it was difficult to pencil in Houck as a certainty to return as a reliable starter. Instead, he was part of a group of candidates vying for that fifth and final rotation spot, alongside Garrett Whitlock, Josh Wincowski and another free-agent addition in Cooper Criswell.

But when Giolito went down in March due to an elbow injury that required season-ending surgery, Houck’s path to reclaim his rotation spot became clearer. With strong springs, he and Whitlock earned the final two rotation spots, meaning Boston’s rotation was deployed as follows:

Game 1: Bello
Game 2: Pivetta
Game 3: Crawford
Game 4: Whitlock
Game 5: Houck

Fast-forward to the midway point of the regular season, and that No. 5 starter has pitched like a bona fide No. 1. So how did we get here?

While Houck’s rapid transformation into one of the American League’s best starting pitchers feels rather sudden considering his recent track record, it’d be disingenuous to refer to him as some kind of anonymous journeyman. After three years as one of the most effective starters in the SEC at Missouri, Houck was selected 24th overall by Boston in the first round of the 2017 Draft. He was developed as a starter until the second half of 2019, when he was moved to the bullpen in Triple-A to prepare him for a possible relief role as part of a wild-card push down the stretch.

Although his MLB debut didn’t ultimately come until a year later during Boston’s forgettable 2020 campaign, Houck established himself as a key member of the big-league pitching staff soon thereafter, albeit in roles that repeatedly evolved. He bounced between the rotation and bullpen over the next two seasons and seemed to be settling into a high-leverage relief role in 2022 before the back injury cut his season short.

Today, fully healthy and cemented atop Boston’s rotation, Houck has reminded everyone why Boston was so excited about him early in his career. Manager Alex Cora says now that he believed Houck was “about to take off” before his unfortunate sequence of injuries and that this past offseason was huge in getting his mechanics back on track.

“Now he's able to repeat his delivery,” Cora said. “His repertoire is what it is — you know, slider, split, and he's still got 94-95 [mph] whenever he wants to. But he's been able to land the split, which is very important.”

Indeed, the most obvious change to Houck’s arsenal is the dramatically increased use of his splitter, a trend we’ve seen with several breakout pitchers across the league. Earlier in his career, Houck used a wicked two-seamer (sinker) and, on occasion, a four-seamer to support his wipeout slider, which has long been his best pitch. In 2024, he has ditched the four-seamer entirely, instead deploying a much more balanced three-pitch attack: 42% sliders, 31% sinkers and 25% splitters (up from 11% a year ago).

On a basic level, Houck’s stuff simply looks nastier than ever, with his slider and his splitter ranking as two of the most impactful individual pitches in the entire league. But stuff has never been a concern with Houck; it was his nearly 9% career walk rate that limited his effectiveness and efficiency over the first four years of his career. This year, he has sliced that number in half, with a 4.3% walk rate that ranks top-five among qualified starters.

“I feel like he's really just grown into his arsenal of what he's really good at,” catcher Reese McGuire told Yahoo Sports. “And I think he's such a great athlete that he can pin-point locations with each one of his pitches. But I think he was too hard on himself before and tried to be so perfect with everything, but now he realizes — and with the help of the staff — that you don't have to be so perfect because the baseball is moving so much.”

Acquired via trade in 2022, McGuire didn’t catch Houck that much the previous two seasons but has been behind the plate for half of his 16 starts this year. From his perspective, the key to Houck unlocking this new level has been enhanced confidence that the sharp movement of his stuff can be effective even without flawless location.

"He's able to create these shapes with his pitches that other pitchers can't create,” McGuire said. “I wouldn't even call them mistakes, but you can get away with missing your spot more than others do because the action of the pitch is still gonna be there.”

As for the evolution of the repertoire, McGuire echoed Cora’s sentiment regarding the splitter’s importance but also emphasized the development of Houck’s fastball command.

“The split's completely been a weapon to both sides, both hands,” he said. “But honestly, for me, I think it's just the command of the two-seam fastball because without the command of his two-seam fastball, it limits him. He becomes more of a one-dimensional pitcher, which is just the slider. Being able to fill the zone up with anywhere from 93 to 97 with the sinker allows the slider and splitter to have such discrepancies from that.”

Houck’s strikeout totals might not wow on the surface, but they shine in tandem with his elite ability to induce contact on the ground. Owner of a 51% career ground-ball rate before this season, Houck has taken it to a career-best 54.5% in 2024. He is one of 11 qualified starters with a GB% above 50%, and of those 11, only Ranger Suarez (26.1%) and Hunter Brown (25.9%) boast higher strikeout rates than Houck’s 24.3%, and Houck’s walk rate is comfortably the lowest among that bunch. It is a downright excellent recipe for run prevention, and his 2.21 FIP nearly matching his league-leading 2.18 ERA emphatically reflects that.

“When you have this stuff that he has,” McGuire said, “fill up the zone with it – that’s what we talk about. Just throw it anywhere in the zone – it's already hard enough to hit. It's already hard enough to plan for as an opposing lineup.”

“It's a unique look, delivery-wise, cross-firing,” Blue Jays manager John Schneider said before his team faced Houck on Monday in the latest of several divisional showdowns the past few seasons. “I think just him being in the zone is a difference-maker for him. You’ve got to be really, really meticulous with pitches that you swing at. He's not going to make many mistakes — but he will — so you’ve got to take advantage of that. But the strike-throwing has been a lot better.”

On Sunday, Boston used eight pitchers in a bullpen game to nail down a series-clinching victory in Cincinnati. It afforded Houck an additional day between starts but also necessitated a lengthy outing from him on Monday.

“I think the day of rest helped him out, and he came in understanding what we needed,” Cora said postgame. “We needed a good one, and it was a good one.”

It wasn’t Houck’s most dominant outing — 6.2 IP, 5 H, 3 R, 2 ER, 1 BB, 7 K — but he pitched into the seventh inning for the ninth time this year and kept Boston within striking distance to enable a dramatic, late-game comeback and eventual walk-off, all with the recently crowned NBA champion Celtics cheering from a suite down the right-field line.

With the extra rest and fueled by an energetic Fenway crowd that Cora described as the best home atmosphere since 2021, Houck showcased his best velocity of the seaso. His sinker touched a season-high 96.5 mph, with all three of his pitches sitting a tick or two hotter than his season averages. But as McGuire noted, Houck's ability to pitch deep into games is appreciated just as much as how his arsenal has leveled up.

“I think that's the best part about Tanner is that he's also getting deeper into games,” McGuire said. “They know how nasty his stuff is, and so a lot of times the opposing lineups are trying to swing at the first pitch or two because they know he's got the wipeout stuff later on. They're trying to jump on him early, but that can also work into our favor where he's getting quick outs.”

With his newfound avoidance of free passes and ability to collect outs via both whiffs and weak contact, Houck’s efficiency has skyrocketed. Only Mariners right-hander Logan Gilbert has pitched deeper into games on average this season. The 103 1/3 innings Houck has racked up through 16 starts have nearly matched his workload from last year (106 innings over 21 outings).

“I feel great physically,” he said postgame, a refreshing acknowledgement considering what he endured the previous two seasons. “Obviously, thank you to the training staff and the coaching staff for looking out for my health because I'd go out there and throw 200 pitches if they would let me,” he continued, half-joking.

For as impressive as his first half has been, Houck clearly has his sights set further ahead — and on doing what it takes behind the scenes to ensure that he can sustain his success down the stretch.

“It's been pretty solid so far, but nothing to really hang my hat on,” he reflected. “There's a reason that the saying goes around that you’ve got to play 162 – because you have to. You have to show up each and every day and do the little things that get monotonous, but at the same time, it's the stuff that helps you get better and helps you prepare for your next outing.

“So coming up on that halfway point, it's great. But there's still a second half to be done.”

Houck will turn 28 on Friday, and he will in all certainty garner his first All-Star Game invite next month. If he can sustain this level of performance in the second half, he’ll be firmly in the AL Cy Young conversation. On a rejuvenated Boston pitching staff that has driven the team’s surprising push into wild-card position, Houck is the definitive headliner.

Not bad for a No. 5 starter.