Tanner Houck Is So Boring That He’s Exciting

Last night, Tanner Houck made his second start since returning from a two-week absence due to arm fatigue, and for the second start in a row, he was absolutely brilliant. Houck threw five scoreless innings, and was perfect through four. Even after surrendering a single and a walk in the fifth inning, he needed just 57 pitches to carve up a struggling Toronto lineup. The Blue Jays have little left to play for this season, and their date with Houck hammered the futility of their situation home even harder. While Toronto starter Chris Bassitt issued a career-high seven walks, Houck averaged just 3.4 pitches per plate appearance. "It's great," he said after the game, "super efficient." He didn’t strike out a single Blue Jay; he didn’t need to. In fact, he was only credited with making one Blue Jay swing and miss all night, but if you listen closely, you can hear that it wasn't a whiff after all. Vladimir Guerrero Jr. very definitely got a tiny piece of it.

Houck also allowed five hard-hit balls, but that didn’t matter much either because all the Blue Jays could manage to do with his pitches was pound them harmlessly into the Rogers Centre turf (though it might not have seemed so harmless to the Toronto groundskeepers, who were left with some major divots to deal with). "Sky's the limit," said Houck, which was ironic considering that 10 of his 15 outs came on groundballs. The outing allowed him to transpose the numbers in his ERA: He started the night at 3.21 and ended at 3.12. The outing also marked Houck's 30th start of the season, the second time he's hit that mark.

The Red Sox are building Houck back up slowly. Last week, he shut down the Rays in a four-inning outing, allowing one earned run with four strikeouts and no walks. Despite checking in with four hits against Houck, the Rays managed an average exit velocity of just 77 mph. Here’s how unusual that was: This season, MLB pitchers had made 4,639 different outings in which they faced at least 10 batters. Houck’s gem against the Rays ranked 4,629th in terms of exit velocity; 11th from the bottom. It was an extremely rare feat.

This is the age of exit velocity and swing-and-miss stuff, and contact managers like Houck are an increasingly endangered species. Despite his dominant performance against the Rays, Houck’s exit velocity numbers aren’t particularly inspiring this season; according to Baseball Savant, his 42.1% hard-hit rate ranks in the 21st percentile. In other words, 79% of MLB pitchers allow fewer hard-hit balls than Houck does. But Houck has learned his own lessons from the launch angle revolution.  Houck has increased his groundball rate in every season of his big-league career. This season, it sits at 55.5%, which ranks sixth among all qualified pitchers. And while his 20.7% strikeout rate puts him in the bottom third of the league, the combination of the two is still impressive. I threw together a quick stat that added together a pitcher’s strikeouts, groundballs, and popups, and then divided it by the total number of batters they faced. In other words, this stat shows the percentage of plate appearances in which the batter registers either a certain out or a batted ball that can’t do anything worse than end up as a single. I set the minimum at 100 batters faced, (which means that this list includes fireballing closers like Mason Miller, who strikes out nearly 42% of the batters he faces). Even amongst that huge sample, Houck checks in at 62.3%, which puts him in the 85th percentile.

On the rare occasion when Houck does allow a fly ball or a line drive – the kinds of batted balls on which batters can do real damage – those balls have an average launch angle of just 24 degrees. This season, 251 pitchers have thrown at least 1,000 pitches, and that launch angle ranks fifth-lowest among them. As a result, the air balls that Houck surrenders travel an average of just 277 feet, putting him in the 82nd percentile. In other words, even if you manage to hit the ball hard against Houck, and even if you somehow manage to avoid hitting a grounder, he still makes it extremely hard to actually lift the ball enough to put it over the fence.  

The exciting this is that Houck’s 3.12 ERA thus far this season has come while inducing all of those grounders in front of the second-worst infield in baseball. According to Statcast’s Fielding Run Values, Boston’s infield has been worth -23 runs this season. Only the Angels have been worse, at -27. If the team can improve its infield defense at all next season – and it would be hard for it to get much worse – a groundball specialist like Houck could benefit in a big way.

According to FanGraphs, Houck’s 3.9 WAR ranks 13th among all pitchers. According to Baseball Prospectus, he’s at 3.6, which ranks 22nd. Houck doesn’t light up the radar gun and he doesn’t blow batters away. Somehow, he’s a sinkerballer whose sinker is his worst pitch. And yet all season long, even while battling through a dead arm, he’s been one of the best pitchers in baseball, simply because he can make batters do just about the most boring thing possible: chop the ball straight into the ground.