Tanner Houck's Future May Be Diverging From the Red Sox

Last season, Tanner Houck emerged. After four years of impressive cameos — including a stint in 2022 out of the bullpen — the big right-hander finally got everything to click in one glorious season. Starting 30 games and logging just shy of 180 innings, Houck turned in a tidy 3.12 ERA (3.32 FIP) while leading the American League in home runs allowed per nine innings (0.6). A confluence of factors finally all went his way, and suddenly, the Red Sox had their first All-Star starting pitcher since Nathan Eovaldi in 2021.

Fast forward to the offseason, and the Red Sox decided to pair their homegrown ace with yet another White-Sox-developed southpaw, Garrett Crochet. The rotation's outlook changed in a hurry, as the team had two surefire pieces atop their staff heading into a crucial season... or so it appeared.

"Surefire" surely wasn't the right term to use for Houck, who has been nothing short of disastrous this season. Through nine starts and 43 2/3 innings, he recorded a ghastly 6.11 FIP, which somehow looks masterful compared to his 8.04 ERA. Nothing was working for him early in the season, as his home run rate skyrocketed, his strikeout rate plummeted, and his walk rate declined from his breakout 2024 campaign. Eventually, the Red Sox had seen enough, placing him on the 15-day injured list with a strained forearm flexor on May 12. That was over two months ago. Now, at last, there is an update on Houck's status, and it is a poor one.

There's no guarantee that this injury ends Houck's season, by the initial prognosis doesn't look good. With no given timetable — and another lengthy rehab assignment likely needed whenever he does feel healthy again — no one can count on him contributing to the cause for the remainder of this season. In conjunction with Hunter Dobbins' season-ending ACL injury, the Red Sox will obviously need to acquire one, if not multiple, starting pitchers at the trade deadline if they have any real hopes of competing down the stretch this season.

But beyond the scope of the team's current playoff chase, Houck's future is now in as much doubt as his status for this year. His batted ball metrics were all in the bottom quartile among MLB pitchers before he got hurt, and only his chase and ground ball rates clocked in above average. Obviously, his injury hampered his performance, but there's more at play than just pure health issues.

Traditionally a three-pitch pitcher, Houck abandoned his seldom-used cutter this year in favor of a seldom-used four-seam fastball. The change didn't yield positive results, as, in 44 offerings, opposing batters hit .600 against the pitch. They posted a ridiculous .839 wOBA and slugged an unfathomable 1.400 against Houck's four-seamer. The sample is tiny, and his expected stats cut all of those numbers practically in half, but suffice to say that pitch, at least in its current form, isn't long for his arsenal.

That's a big problem considering that Houck has yet to find a fastball that really suits his pitch mix. He relies on a sinker as his primary heater, but hitters were slugging .533 against that pitch this year, too. Even last year, when Houck's sweeper and splitter were performing better than ever, batters still had an expected slug (xSLG) of .453 and an xwOBA of .382 against the sinker. And, before anyone cites velocity concerns due to his arm issues, it should be noted that Houck was throwing his sinker a whole mile per hour faster this season than last, and his four-seamer was hit 95 mpg on average.

A big part of the reason that the team has tried to get Houck to implement a four-seam fastball is his strict movement profile. He's always been tremendous at changing hitter's hand positioning by pitching them inside and outside with pitches that move a lot along the horizontal plane, but take a look at his pitch chart for this year and note how limited the change in movement is across his pitches on the y-axis:

His breaking pitches don't sink much and his heaters don't rise much. That's not a recipe for success, and it makes changing hitters' eye levels practically impossible. For a reliever, that kind of arsenal can have some success, but when a starter has to go multiple times through an order, hitters can catch on pretty quickly to the gambit. For those wondering, this same issue was even more exacerbated last year, though his splitter had more vertical drop variance and he threw his sweeper more often than his sinker, which, in my estimation, is his best opportunity to succeed as a guy who likes to pitch backward.

None of this condemns Houck to a future in the bullpen or Triple-A or anything like that, but if Houck, 29, is going to be successful in the long-term, he's going to need a reliable fastball. Are the Red Sox the right organization to help him unlock that pitch once he returns from injury? Perhaps, but given their proximity to contention, they may not be able to afford finding out, at least at the major league level.

Don't expect a trade while his value is as its lowest, but in just four months, Tanner Houck has gone from "surefire" No. 2 starter to an injury-riddled reclamation project. If someone else prefers to handle the fixer-upper, it wouldn't be the worst decision for the Red Sox to hand him off.