What the heck happened to Nathan Eovaldi on Friday?

It goes without saying that Nathan Eovaldi did not get the job done on Friday. In what was his most important outing of the year, he came out with his worst performance of 2021, giving the Red Sox a convincing loss in what could have very well been a Wildcard Game Preview. The righty couldn’t even make it through three full innings on the day, getting charged with seven runs over 2 ²⁄₃ and most notably not tallying a single strikeout. Scientifically speaking, it was not what you want.

It’s probably a bit hasty to declare this as any sort of long-term concern. Eovaldi has been outstanding for Boston all year, entering the day with a 3.58 ERA and a 2.72 FIP. He’s been particularly good in this second half, too, starting to strike out more batters and really turn it on. One bad outing does not cancel out all of that, of course. And it would certainly be silly to say anything about his ability to perform under pressure given the entire 2018 playoff run. But at the end of the day, this was still a really bad outing at a really bad time, and it’s worth taking a deeper look at just what the heck happened.

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And really, on the most basic level it’s not really some big mystery. We mentioned it above. Eovaldi has been really rolling these last couple of months, and the big change has been his strikeout rate. Despite the velocity, he had never really been anything near an elite strikeout pitcher in his career, and after carrying a strikeout rate around 23 percent over the first three months, he struck out 28 percent of batters in July and August, and entering this last start had a 35 percent rate in September.

And again despite the velocity, it’s not really because of the fastball that he’s getting all of his strikeouts. The fastball is still a key offering for Eovaldi, of course, as the threat of upper 90s being in the back of opponents’ mind is never a bad thing. But his whiff rate has really risen of late on his secondaries, and in particular with his splitter, curveball, and slider. Those, along with the fastball and cutter (though he’s cut back on his cutter usage in the second half, and that trend continued on Friday), create a five-pitch mix that has been keeping hitters off balance. When it’s all working, it’s easy to be caught guessing, and then striking out.

But the secondaries just were not good on Friday and the Yankees never appeared to be uncomfortable. For the whole game, Eovaldi only induced three swinging strikes, and oddly enough they all came on fastballs. While the slider didn’t generate any whiffs, the location actually wasn’t terrible with those pitches. Really, it was the curveball and splitter that caused issues.

Neither of those pitches were being located at all. With the splitter, Eovaldi just didn’t have a feel for it and only threw it five the whole game, just eight percent of his pitches. He’d been throwing it at about double that rate the last few months. And it’s not hard to see why he didn’t want to throw it, given the zone plot below. That one that caught the zone was an early double from Aaron Judge that easily could have been a home run.

Four of those five splitters were thrown in the first inning, after which he mostly ditched it. That wasn’t a luxury he had with the curveball, as he had to have some sort of offspeed pitch in his back pocket. But like the splitter, he wants to get that pitch down, and specifically on the glove side on the outer half against righties. He got a few down in that zone, but they were largely non-competitive. And many more were just nowhere near the target area.

Pitchers are entitled to a bad outing, though this one was certainly terribly timed. But the key for the Red Sox is, of course, getting Eovaldi back on track, particularly for a potential Wildcard Game start. And the key is always going to be having his pitches working. He still gets by largely by pounding the zone, but he’s reached another level by missing more bats, which in turn is the result of a top-notch pitch mix. We’ll be looking for the command on these secondaries next time out, and if he’s struggling to get the feel for these key pitches early on, we know that could spell trouble.