Article: What’s Wrong With Tanner Houck?

Nick John · April 17, 2025

Tanner Houck was the Red Sox ace in 2024. He's now sitting on a 9.16 ERA. What's going on?

Monday night saw the Boston Red Sox get completely destroyed by the Tampa Bay Rays, losing 16-1. While it was an ugly game all around, it was especially bad for starter Tanner Houck. Houck struggled from the get-go and failed to make it out of the third inning. In total, Houck pitched 2 1/3 innings, allowing 12 runs, 11 of them earned, on 10 hits. The right-hander also allowed two walks while striking out only a single batter. He threw 61 pitches, meaning that he averaged 5.1 pitches per run. The 10 hard-hit balls he allowed outnumbered his nine swinging strikes.

Houck had trouble finding the zone, though his 26.5% chase rate was a slight improvement on his full-season mark. There was some talk that Houck may have been tipping his pitches, especially as he had a similar pitching line when he threw against the Rays near the end of spring training. Houck’s struggles may be a bit deeper than that, however.

Houck Pitch Chart.jpg

The right-hander had a rough spring, and his struggles carried over into the regular season. He has not looked like the All-Star pitcher he was a year ago. Some hoped he'd turned a corner after an excellent start against the Blue Jays, pitched into the seventh inning and only surrendering a single run despite frigid temperatures. That was not the case. A deeper look into Houck's season so far raises some interesting concerns.

First off, ditching his four-seam fastball entirely in 2024, he’s gone back to it a little bit in 2025. So far, he's thrown it 7% of the time. On Monday night he threw six four-seamers, all of them in the zone, but none put in play. In 2024, Houck was practically a three-pitch pitcher, relying on his sweeper, sinker, and splitter for roughly 98% of his pitches. Unfortunately, advanced stuff metrics like Stuff+ and PitchingBot say that the four-seamer is much worse this year than it was in 2023.

Houck's sinker isn't sinking like it did last year. In 2024, his average movement on a sinker was 16 inches of horizontal break and an induced rise of 0.4 inches. In 2025, those numbers have increased to a tail of 17.1 inches and a rise of 1.1 inches. He's also leaving the pitch over the middle of the plate much more often, rather than hitting the edge, and opponents are batting .407 and slugging .741 against the pitch.

Houck's splitter is getting hit hard as well, and the issue seems to be more about location than break, as he's no longer locating on the edge of the plate like he did in 2024. His splitter has mostly been used against lefties, and when he keeps it down and away, he's successful. He's been leaving it out over the plate, however, and the pitch has a .389 batting average.

The sweeper might be the least of his concerns, as it's generated the most of his whiffs at 34.1% and has been a solid putaway pitch, resulting in nine strikeouts. The pitch is a bit tighter this year, losing two inches of horizontal break. The sweeper has been a pitch he’s been able to rely on so far, but if he can’t get the other two pitches to get back to their 2024 state, he may be in for a rough season.

The lack of strikeouts has definitely been Houck's biggest issue, and location is a big piece of the puzzle. His pitches have been catching a lot more of the middle of the plate, and when he's missed the zone, he's missed by too much to induce chases. His strikeout percentage has dropped from 20.7% in 2024 to 12.6% in 2025, while his walk percentage has risen from 6.5% to 10.3%. Add to that a hard-hit rate of 54.5%, and it's clear that not much is going right for Houck.

The combination of worse stuff and worse location is hard to overcome. Houck isn't missing bats or inducing soft contact like he once did. The biggest change may be his fly ball rate. His career rate sits at 19.4%, but he's currently at 24.2%. WHouck should be trying to get batters to be on top of his sinker and splitter, driving them into the ground. When he does that, he can rely on the team's improved infield defense, especially when he struggles to generate whiffs. Instead, batters have been getting under the ball, driving them into the air with force, as we saw in the two home runs that Houck allowed on Monday.

There’s no denying that something is wrong with Houck to begin the season. It could be something mechanical, or he could just be struggling to find his rhythm. But if the Red Sox are going to have a shot at a playoff run, they will need Houck to figure it out.

View full article