Luis Castillo Hasn't Seemed Like Himself Recently - This Might Be Why

What has caused the team's ace to get off to such a rocky start in 2024? Looking into why Luis Castillo has struggled to start in 2024

Cleveland Guardians v Seattle Mariners
Cleveland Guardians v Seattle Mariners / Alika Jenner/GettyImages
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Since arriving in Seattle towards the 2022 trade deadline, Luis Castillo has been a loyal and effective ace, leading one of the best rotations in baseball. Prior to the start of this season, he was even in the conversation to be a serious contender for the AL Cy Young award. Unfortunately, he hasn't lived up to those expectations so far. If anything, he's far from them. Over his past two starts, he has pitched to a 6.75 ERA and 1.78 WHIP over 10 ⅔ innings. So what's going on?

The four-seam fastball isn't landing high and tight like he wants

To start, let's look at Castillo's bread and butter: the four-seam fastball. It's been his most frequently thrown pitch ever since he became a Seattle Mariner and gradually dialed down the usage of his changeup. While his velocity is still around the same as it usually is (averaging 95.8 mph), the command has definitely regressed.

It's been frequently discussed just how effective it is for pitchers, especially those with velocity >95 mph, to attack hitters high and inside with their fastball. For the fastballs he threw in 2023, most of the whiffs landed in the upper corners. In 2024, he's seen a lot more spread and more importantly, more of his fastballs are ending up closer to the middle portion of the zone. Even when landing pitches on the inside, hitters have gotten so good at pulling their hands in that if the pitch isn't high enough, hard contact is still a very distinct possibility. A great example of this is Bo Naylor's home run which was on a four-seam fastball on the inside. Naylor ended up hitting the pitch 383 feet.

The sinker isn't running enough for Luis Castillo

While he hasn't used it as much as his four-seam, the sinker is also causing some problems. Opposing batters are currently slugging 1.000 against the pitch over 6 PAs including a home run to Rafael Devers on Opening Day.

While the sinker is often a great pitch to throw to opposite-handed batters, especially one with great arm-side run like Castillo's, it only works if you get it to clear the barrel. When pitching to Devers, the pitch remained in the zone enough for him to get great contact.

A great example of what to do instead would be this great sinker that Brewers reliever Abner Uribe threw to lefty Jack Suwinski last year. Because it has so much run and is placed well, there's nothing Suwinski can even to make contact, aside from taking a page out of Elastigirl's book. Add some vertical break and you've got yourself a nasty pitch.

With Castillo, he's getting good movement but because the pitch starts too close to the middle of the zone, it's not enough for it to ride the edges and make it hard for good contact to be made. Thus, he must either 1) start the pitch closer to the arm side of the zone or 2) add a few more inches of run. The second option is quite a bit harder in my opinion (I have never once thrown a sinker in my life).

What might also be contributing to these command/placement issues is a decrease in spin rate. Castillo lost 88 RPM on his four-seam fastball and 84 RPM on his sinker compared to last year's averages. This might actually fix itself as he continues to warm up throughout the season but it's worth highlighting nonetheless. The sticky substance epidemic of 2021 showed us just how effective an increase in spin rate is so it makes sense that a lower spin rate might be contributing to a regression in pitch performance.

There are some issues to iron out if Castillo wants to get back on track but fans shouldn't lose hope just yet. He's a veteran major leaguer for a reason and he'll likely get back on track sooner rather than later. The good news is that he isn't seeing dramatic decreases in velocity and we're still only ten innings deep into what will likely be another 170+ inning season from him. To me, "La Piedra" still has a chance to turn things around and return to rock-solid form.