Champ or Chump: Luis Castillo

Nothing is worse for a fantasy manager than when an early-round pick puts up disastrous numbers. You can't start the guy because he's brutalizing your ratios, yet you can't drop him because you've invested too many resources to give him up for free. What if he turns it around in his next appearance and you miss out? What if he never gets going?

Luis Castillo of the Cincinnati Reds is putting fantasy managers through this conundrum so far in 2021. With an ADP of 28.4 per FantasyPros, he was expected to be an anchor in a year with unpredictable pitching. Unfortunately, going 1-3 with a 6.07 ERA over 29 2/3 frames is not what his managers expected. He isn't contributing in the strikeout department either, producing a 17.9 K% after eclipsing 30% in 2020 and approaching it in 2019. It has been ugly.

The real question is whether Castillo will continue to struggle or if he ultimately rights the ship. Honestly, the answer probably lies somewhere in between.

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The Luck Stats

Experienced fantasy gamers know that several metrics give you some insight into the sustainability of a pitcher's performance. Luck isn't the only thing that goes into these numbers, but it's a quick and dirty way of grouping metrics like HR/FB, strand rate, and BABIP together for subheading purposes.

Anyway, most of these metrics suggest a return to form for Castillo. Castillo's 23.8 HR/FB is unbelievably bad, making home runs a problem for a pitcher who only has a 22.1 FB%. His career rate is elevated at 17.6% thanks in part to the Great American Bandbox, but regression should still prove favorable.

Likewise, there is no way that Castillo deserves his .368 BABIP allowed. The issue thus far has been a 25.3 Line Drive% that's substantially higher than his career mark of 19%. LD% generally isn't predictive of anything, especially in one-month samples, so this issue should resolve itself. Castillo's career BABIP is .282, and that seems like a reasonable projection moving forward.

Finally, Castillo's 60.5% strand rate is very low. His career mark is 73.4%, but you typically need strikeouts to post a strand rate that high. Since Castillo's Ks have dried up, a lower strand rate is to be expected. Thus, we need to figure out why Castillo's K% is down to determine if his strand rate will return to normal.

Castillo's Pitch Mix

The best way to figure out if a K% change is real or a mirage is to examine the pitcher's repertoire. Castillo is a four-pitch pitcher with an arsenal consisting of his trademark changeup, a four-seam heater, a sinker, and a slider. This season, he's throwing more changeups (30% in 2020 vs. 39.4% this year) at the expense of his sinker (25.3% to 19%) and slider (17.7% to 14.2%). That should be a good change considering that his changeup is his best pitch, but its efficacy is down.

Opposing batters are chasing Castillo's change out of the zone at a whopping 50% clip, and the resulting 16.6 SwStr% isn't bad at all. However, opposing batters have always chased the offering with a 46.2% chase rate over Castillo's career and usually have even less luck with a 24.7 SwStr%. The offering's 38.5 Zone% is also low for a pitcher's most-used offering, though Castillo's 6.0 BB% suggests that walking guys is the one problem he's not having.

Castillo's sinker stinks. Batters are obliterating it to the tune of a .464/.545/.821 triple-slash line this season, and its career line of .296/.361/.453 suggests that it's always been his weakest offering. As such, it's tough to argue that featuring the pitch less frequently is the problem here. Castillo's slider is more of a show-me pitch than a true weapon, producing a 15.2 SwStr% backed by just a 20% chase rate in 2020. This season, batters are swinging at it more often with a 31.7% chase rate but also making more contact with an 8.1 SwStr%. Again, the difference isn't stark enough to explain Castillo's troubles.

Some have speculated that Castillo's velocity loss is the root of his troubles, but the metrics don't really support that conclusion. The 96.6 mph he's averaging in 2021 is indeed less than the 97.6 he averaged last season, but he succeeded in 2019 with "just" 96.3 mph. Castillo's 15.8 SwStr% on his fastball in 2020 was almost certainly too good to sustain for a full season, but it's performing at 2019 levels (8.5 SwStr% this season, 8.7% in 2019). A downgrade from 2020, sure, but certainly not unrosterable.

It could be a spin rate issue. Castillo's fastball averaged 2,188 RPM in 2020, of which 91% was active spin (or spin that contributed to a pitch's movement). His active spin is down to 83% this season, but his raw RPM increased to 2,269. The net result favors 2020 and may have something to do with why his changeup is underperforming its career numbers, but all of these numbers are dwarfed by pitchers like Max Scherzer. Realistically, the conclusion here is that fantasy managers should've realized that Castillo's fastball SwStr% last season was a mirage since he didn't have the spin to support it.

Other Variables and Conclusions

Castillo has a reputation for pitching best in warmer weather and his starts have seen some terrible conditions. It was 37 degrees for his Opening Day start, 20 mph Bay Area winds for his third start, and snowing for his fourth start. His fifth and sixth starts were in the 60s with about 10 mph winds, while his seven-inning gem against the Pirates took place on a 77-degree day. As it warms up, Castillo may start having better results.

Of course, a fantasy ace probably shouldn't be so concerned with the weather. Castillo didn't have the spin rate to support his elite 2020 fastball, a factor that should have been reflected in his draft day price but wasn't. Baseball Savant's xStats say that Castillo has pitched better than his stats look with a .303 xBA against a .328 BAA and .502 xSLG to .576 SLG, and his expected stats get better if you assume that his LD% declines.

Normalizing Castillo's HR/FB brings him to a 3.75 xFIP, but Baseball Savant is more pessimistic with a 4.85 xERA. That is a stark difference, with his xFIP suggesting fantasy viability while his xERA is a streaming option at best. This author leans that the strikeouts will return since any degradation of stuff is minimal, but I cannot guarantee anything. Castillo doesn't look like an ace either way, but you shouldn't sell him for pennies on the dollar either.

Whether he's a Champ or a Chump depends on your criteria. The author has the luxury of slotting him as an SP5 behind Shane Bieber, Aaron Nola, Walker Buehler, and Kevin Gausman in one keeper league, and he's a Champ in that scenario. If Castillo was supposed to lead a rotation that's otherwise full of question marks, he's probably a Chump for you. The season's first split decision!

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