Every baseball season brings a new wave of surprising players, those who rise from the lowest levels of the depth chart to full-blown stardom in the blink of an eye. This year, amid a first half filled with surprising and unexpected pitching performances across the league, Red Sox right-hander Tanner Houck – the current American League ERA leader and leads in fWAR among qualified starting pitchers — stands out as a particularly notable climb.
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 advantages beyond that. Brayan Bello, who signed an extension before Opening Day, was Boston’s leading starter in 2023. Kutter Crawford and Nick Pivetta also made big strides as rotation members last year and seemed like safe bets to repeat in those roles.
Although Houck also finished 2023 in the Red Sox rotation, he had much more to prove entering 2024. It was a challenging period 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 frightening injury that cost him two months. Navigating two wildly different but significant rehabs made it difficult for Houck to find his rhythm, and he finished last season with a 5.01 ERA in 21 starts, ranked 54th out of 65 AL starting pitchers with at least 100 innings pitched.
As a result, at the start of this year’s camp, it was difficult to pin Houck down as a certainty to return as a reliable starter. Instead, he was part of a group of prospects vying for the fifth and final spot in the rotation, alongside Garrett Whitlock, Josh Wincowski and another free agent addition, Cooper Criswell.
But when Giolito went down in March with an elbow injury that required season-ending surgery, Houck’s path to regaining his rotation spot became clearer. With strong springs, he and Whitlock won the last two rotation spots, meaning Boston’s rotation was deployed as follows:
Game 1: Beautiful
Game 2: Pivetta
Game 3: Crawford
Game 4: Whitlock
Game 5: Houck
Fast forward to the middle of the regular season and the 5th starter 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 seems quite sudden considering his recent track record, it would be disingenuous to refer to him as some sort of anonymous journeyman. After three years as one of the SEC’s most effective starters 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 attack down the stretch.
Although his MLB debut didn’t 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 after, albeit in roles that evolved repeatedly. He bounced between the rotation and the bullpen over the next two seasons and appeared to be settling into a high-leverage relief role in 2022 before a back injury cut his season short.
Today, fully healthy and cemented in Boston’s rotation, Houck reminded everyone why Boston was so excited about him early in his career. Coach Alex Cora now says that he believed Houck was “about to take off” before his unfortunate run of injuries and that this past offseason was important in getting his mechanics back on track.
“Now he can repeat the delivery,” said Cora. “His repertoire is what it is – you know, slider, split, and he’s still 94-95 [mph] whenever he wants. But he got the division, which is very important.”
In fact, the most obvious change in Houck’s arsenal is the dramatic increase in his splitter usage, a trend we’ve seen from several emerging pitchers across the league. Early in his career, Houck used a two-seam sinker (sinker) and occasionally a four-seam to support his slider, which has long been his best pitch. In 2024, he abandoned 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 splitter ranking as two of the most impactful individual selling points across the league. But things were never a concern for Houck; it was his career walk rate of nearly 9% that limited his effectiveness and efficiency during the first four years of his career. This year, he cut that number in half with a 4.3% walk rate, which ranks in the top five among qualified starters.
“I feel like he’s really grown in his arsenal of what he’s really good at,” catcher Reese McGuire told Yahoo Sports. “And I think he’s such a good athlete that he can identify spots on each of his pitches. But I think he was very hard on himself before and tried to be so perfect in everything, but now he realizes – and with the help of the team – that you don’t have to be so perfect because baseball is moving so much. ”
Acquired via trade in 2022, McGuire didn’t reach Houck much the previous two seasons but was behind the plate for half of his 16 appearances this year. From his perspective, the key to Houck unlocking this new level was increasing confidence that jerking his stuff can be effective even without perfect location.
“He’s able to create these shapes with his pitches that other pitchers can’t create,” McGuire said. “I wouldn’t even call it mistakes, but you might miss your point more than others because the action of the field will still be there.
As for the evolution of the repertoire, McGuire echoed Cora’s sentiment regarding the importance of the splitter, but also emphasized the development of Houck’s fastball command.
“Division has been a weapon for both sides, for both hands,” he said. “But honestly, for me, I think it’s just two-seam fastball command, because without two-seam fastball command, it limits you. He becomes more of a one-dimensional pitcher who is just the slider. Being able to fill the zone somewhere between 93 and 97 with the sinker allows the slider and splitter to have such discrepancies relative to that.
Houck’s strikeout totals may not be impressive on the surface, but they shine in conjunction with his elite ability to induce contact on the ground. Owner of a career 51% ground ball rate before this season, Houck has achieved 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%) have higher strikeout rates than Houck’s 24.3%, and Houck’s walk rate is comfortably the lowest among that group . It’s an absolutely excellent recipe for run prevention, and his 2.21 FIP nearly matching his league-leading 2.18 ERA emphatically reflects that.
“When you have those things that he has,” McGuire said, “fill the zone with them — that’s what we talk about. Just throw it anywhere in the zone – it’s strong enough to hit. It’s hard enough to plan like an opposing lineup.”
“It’s a unique look, in terms of delivery and crossover shooting,” Blue Jays manager John Schneider said before his team faced Houck on Monday in the latest of several divisional matchups over the past few seasons. “I think just him being in the zone makes a difference for him. You have to be very, very meticulous with the shots you make. He won’t make many mistakes – but he will – so you have to take advantage of that. But the throwing of strikes has been much better.”
On Sunday, Boston used eight pitchers in a bullpen game to secure a series-clinching victory in Cincinnati. This provided Houck with an additional day between games, but also required a long outing for him on Monday.
“I think the rest day helped him and he understood what we needed,” Cora said after the game. “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 in the seventh inning for the ninth time this year and kept Boston within striking distance to allow one dramatic return at the end of the game and eventual departure, all with the newly crowned NBA champion Celtics cheering from a suite on 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 presented your best speed of the season. His sinker hit a season-high 96.5 mph, with all three pitches a point or two hotter than their season averages. But as McGuire noted, Houck’s ability to throw deep into games is appreciated as much as the way his arsenal has leveled up.
“I think the best part about Tanner is he’s also getting deep into games,” McGuire said. “They know how nasty his pitch is, and a lot of times opposing lineups try to hit on the first or second pitch because they know he’s going to have the destruction pitch later. They’re trying to attack him early, but that can also work in our favor when he gets quick outs.”
With his recent free pass avoidance and ability to collect eliminations through whiffs and weak contact, Houck’s efficiency has skyrocketed. Only Mariners right-hander Logan Gilbert has gone deep in games on average this season. The 103 1/3 innings Houck accumulated in 16 starts nearly matched his workload from last year (106 innings in 21 starts).
“I feel really good physically,” he said after the game, a refreshing acknowledgment considering what he had suffered over the previous two seasons. “Obviously, thank you to the coaching staff and the coaching staff for looking out for my health, because I would go out there and throw 200 shots if they let me,” he continued, half joking.
As impressive as his first half was, Houck clearly has his sights set on the future – and on doing whatever is necessary behind the scenes to ensure he can sustain his success in the future.
“It’s been pretty solid so far, but nothing I’m really excited about,” he reflected. “There’s a reason it says you have to play 162 – because you have to. You have to show up every day and do the little things that get monotonous, but at the same time, it’s what helps you improve and prepare for the next outing.
“So, getting halfway there, it’s great. But there is still a second half to be done.”
Houck will turn 28 on Friday and will almost certainly receive his first invitation to the All-Star Game next month. If he can maintain this level of performance in the second half, he will be firmly in the AL Cy Young conversation. On a rejuvenated Boston pitching staff that led the team’s surprising push to wild card position, Houck is the definitive headliner.
Not bad for a number 5 starter.
