What to make of Nathan Eovaldi’s early-season homer issues

Last year was Nathan Eovaldi’s 10th in the majors, a significant feat no matter how someone gets there, and for him specifically it was his best season in the bigs. He transformed the way he pitched and showed the sharpest stuff of his career, ending the year among the Cy Young vote-getters. His candidacy for that specific award was largely based around “new school” stats looking at his great peripherals rather than his good, but short of great, results. Early on this season, through three starts in 2022, Eovaldi is getting similar results (actually slightly better), but the peripherals are telling a different story, and that is largely coming down to a handful of home runs he has given up early on this season.

If you look beyond those long balls — and there is some level of a “other than that, how was the play Mrs. Lincoln?” vibe here, but humor me — it’s been a strong start for Eovaldi. The team ace has pitched 14 ²⁄₃ innings over three starts, so there’s been some inefficiency as well, but he’s struck out 19 while walking only three in that time. He’s also not giving up a ton of hits, allowing just a .297 batting average on balls in play, a bit better than he’s allowed in recent years.

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But the homers are really making his starts more difficult than they otherwise would be, and they’re coming in bunches in a way we simply did not see last season. Eovaldi, through those three starts, has now allowed five homers. In 2021, he didn’t allow his fifth home run until July 6 against the Angels, his 18th start of that season. Of course, we are still firmly in the Small Sample Zone of this baseball season, and that’s what a stat like xFIP aims to keep in mind, normalizing a pitcher’s home run to fly ball ratio to say what their peripherals would look like in a normal sample. I have issues with the idea that we should expect all pitchers to have a similar home run to fly ball ratio, but in this sample it’s worth entertaining Eovaldi’s 2.64 xFIP. Or, paying less attention to the specific number and more to the context of the stat: Is there something to worry about here with the homers, or is this just weird small sample size trends?

The obvious place to start here is looking at the quality of contact Eovaldi is giving up, which is not very encouraging. As mentioned above it’s not resulting in a ton of hits judging by his BABIP, but opponents are hitting the ball hard. Early on, the average ball against Eovaldi has been hit nearly 93 mph, and batted balls have been hit at least 95 mph (i.e., a hard-hit ball) over 52 percent of the time. Both of those numbers would be career highs by a long shot, and each puts him in the bottom 11 percent among all pitchers. Looking at the average exit velocity on pitches he’s thrown in the zone is a good visualization for the kind of contact he’s allowed thus far.

The thing is, if you are looking for reasons why this is happening, the answers are much less clear and it’s hard for me to not still come back to simply small sample size weirdness. The closest thing to an individual pitch that is most to blame would be his slider, which is the only one of his five offerings off of which opponents have hit multiple homers. He’s allowed two homers with the slider, and it’s been his worst pitch thus far. His whiff rate is down from 35 percent last year to 21 percent this year, and on average it’s being hit 93 mph compared to 87 mph a season ago.

The thing is, he’s only allowed eight batted balls against the pitch, hardly a representative sample, and there are not major differences to point to explaining this. Eovaldi’s spin rate is actually a bit higher on the pitch, the location is a bit spotty, but he made mistakes last season, and the movement profile is roughly the same as we saw in 2021.

And that’s a similar story with his other pitches as well. The slider is the only offering on which he is inducing significantly fewer whiffs compared to 2021, but beyond that he’s also giving up harder contact despite similar stuff in terms of velocity, spin, and movement. The last thing I could think of here in terms of tangible issues leading to the hard contact and homers would be sequencing. It’s harder thing to research to be sure, but what stands out looking at Brooks Baseball’s usage tables is that he is approaching lefties differently than he did in 2021. Specifically, he’s starting off lefties with curveballs more often this year, and lefties are hitting him harder than righties, which is to be expected. My hypothesis here is that the extra first-pitch curveballs is leading to more 1-0 counts, which may not be resulting in walks but perhaps is forcing him into more hitters counts where batters are sitting on, and getting, fastballs to hit.

All of that being said, there’s just nothing concrete enough here for me to say that this is something to worry about. Baseball is a game of adjustments and he certainly needs to keep making sure he’s adjusting to how batters are approaching him, and maybe he should make a tweak with his slider specifically or just throw it less. But ultimately, the stuff still looks good, and his individual pitches are still being thrown how he wants them to be thrown. It’s certainly something to monitor moving forward, but I don’t think we’re particularly close to the point where we really have to worry about this issue.

Thanks to Baseball Savant and FanGraphs for data in this post.