The Mystery of Justin Verlander’s Home Runs

In the second half of the season, Justin Verlander has been the best pitcher in baseball. On the heels of a no-hitter over the weekend, Verlander lowered his second-half FIP to a major league-leading 1.91 and his ERA to an AL-leading 1.76, and raised his WAR to 3.2, more than half a win better than second-place Jack Flaherty. On the season, it’s less clear whether Verlander has been the game’s best pitcher. His 2.56 ERA does lead the AL, but his 3.41 FIP is seventh in the league, and even with his 193 innings tops in the game, he’s still nearly a full win behind Lance Lynn in WAR, with Gerrit Cole and Charlie Morton ahead of Verlander’s 5.2 figure as well.

The reason Verlander has performed relatively poorly — even if he’s only the fourth-best pitcher in the AL, he’s having a great season — is due to all of the home runs he has given up. Only Mike Leake and Matthew Boyd have allowed more than the 33 homers offered up by the 36-year-old righty. In some ways, Verlander’s home run troubles are just an extension of the 2018 season. Home runs have gone up from 1.16 per nine innings last year to 1.45 this year; Verlander gave up 1.18 homers per nine innings last year and has given up 1.54 this season. Even if Verlander’s increase was exactly in line with the rest of baseball’s, we’d only be talking about a difference of two home runs, and a 3.28 FIP instead of the 3.41 he currently holds. But that’s still a pretty big difference from his 2.69 ERA, and requires some explanation.

The simple answer behind all of Justin Verlander’s homers is that he’s a fly ball pitcher who throws pitches more prone to homers than most pitchers. A year ago, it might have been that Verlander was a bit unlucky with the long ball. Based on Statcast’s numbers, Verlander’s xwOBA on homers last year was 1.042, which was about 300 points below league average, so he might have had his share of bad luck in that regard. This season, the xwOBA on Verlander homers is 1.317, right in line with the rest of the majors. The same is true when we drop the standards to batted balls with an expected ISO of at least .200. Verlander’s xwOBA on those 97 batted balls was .876 compared to a major league-wide .857, and the resulting wOBA for Verlander was .921 compared to .902 for the rest of the sport. Twenty-five percent of those balls ended up out of the ballpark for the league compared to 31% for Verlander, which isn’t a huge difference. Based on the quality of the contact, Verlander has absolutely earned his home run totals this season.

I looked into the pitch types and locations for Verlander’s home runs. More than half of his homers were in three fairly distinct categories:

• Eight homers to righties on fastballs down the middle, middle-low, and middle-away, but still in the heart of the plate.
• Seven homers to lefties on fastballs at the top of the strike zone.
• Four homers on sliders down the middle.

Across those three categories, I found that Verlander threw those pitch types in those locations more often than other pitchers with similar pitches and velocity, which might lead to some predictability to his pitches, though clearly not enough to prevent him from getting hitters out the vast majority of the time. He challenges hitters and it works most of the time, but that same approach might make him slightly more vulnerable to homers. In short, Verlander gives up a lot of home runs because he throws a lot of pitches where batters hit home runs.

The other side to the home run issue is to wonder why, if Verlander isn’t giving up many runs overall, it matters? But if we’re trying to accurately gauge his talent and worthiness for postseason awards, it’s necessary to compare him to other pitchers. Just looking at ERA can give too much credit or blame based on defense and ignores the effects of the ballpark and the league. Another way to value pitchers is to use a FIP-based WAR, but the home runs complicate things, as FIP’s perceived value for Verlander is lower than a strictly run-based system.

There is an argument to be made that Verlander’s FIP doesn’t accurately represent his talent because he pitches differently with runners on base, and tends to allow more solo homers than multi-run shots. Jay Jaffe discussed this phenomenon a bit in June when he wrote about Verlander’s dominance despite the dingers. With the bases empty, Verlander has given up 1.8 homers per nine innings; with runners on base, it is just 1.0 home run per nine this year.

Verlander’s xwOBA doesn’t diverge markedly between the two situations, with only a 13 point gap (.252-.239), but the solo home runs suggest that how he goes about getting to those numbers differs. Verlander is probably pitching differently with runners on in a way that limits homers, as he throws fewer fastballs and more sliders and elicits a higher groundball rate. But the issue with trying to lighten the importance of his FIP relative to other pitchers is that many other pitchers do the exact same thing. Verlander has reduced his homers by 44% once runners get on, but the average starter experiences a 13% reduction in homers based on the situation. Lance Lynn has an 70% drop in homers with runners on base compared to the bases empty, and Lynn’s pitch strategy with runners on base is even more extreme than Verlander’s.

The above is not to say that we shouldn’t make some sort of mental adjustment for Verlander’s homers, but rather that other pitchers might need that same adjustment as well. The reason we’re inclined to make that mental adjustment for Verlander is the big gap between his ERA and FIP; Lance Lynn doesn’t have that gap at all, so we might tend to think his homer totals are just normal. When a pitcher has a significant gap between his ERA and FIP, the most likely culprits are left-on-base percentage and BABIP. Verlander’s LOB% is 90.1%, more than seven percentage points higher than second-place Clayton Kershaw. If it holds, it would be the highest LOB% ever. His .202 BABIP is likewise the best in baseball this season, this time by 42 points over Jeff Samardzija, and would be the lowest BABIP since Ed Ruelbach in 1906.

While Verlander is likely partly responsible for some of these figures, they are such incredible outliers that other factors are probably involved. First, there’s the Houston defense, which is very good this season. The Astros as a team are first in baseball in both BABIP against and LOB%. These aren’t factors unique to Verlander, but are brought about by the team he plays for. On balls in play this season, Statcast’s xBA says Verlander’s contact quality should yield a .258 BABIP. The more than 50-point gap between his xBA on those pitches and the actual BA is fifth-highest out of 152 pitchers with 200 batted balls. That’s an extra 20 outs due to positioning, defense, and luck. Those 20 outs means 20 fewer batters at first glance, but another five or six of those hitters get on base and put more runners at risk of scoring. The cumulative effect of those outs is roughly a full start of shutout ball. Similarly, Verlander’s wOBA on balls in play is nearly 70 points lower than his xwOBA, the eighth-highest total in the game. League-wide, the difference is around 30 points, but even looking at 40 points of xwOBA is around 15 runs difference across Verlander’s 433 PA against. Adding 15 runs to Verlander’s total this season would make his ERA 3.26, nearly in line with his 3.41 FIP.

The mystery behind Verlander’s gaudy home run totals isn’t really much of one. He’s a homer-prone pitcher making homer-friendly pitches among his strikeout-inducing, walk-avoiding offerings. That’s who he was before this season and he stepped into a year where balls are reaching the seats like never before. What the home runs are doing is obscuring the real argument about how well Verlander is pitching, and clouding the benefits of playing in front of a good defense (and never having to face the Astros offense). Verlander is having another great season, one that merits Cy Young award consideration if not the award itself, but the home run question shouldn’t push his FIP close to his ERA when we contextualize Verlander’s year. Rather, it’s the Astros defense that should be pushing his ERA towards his FIP.