In 2017, Luis Castillo of the Cincinnati Reds was arguably one of bright spots of the season. Castillo burst on the scene with a 3.12 ERA and 98 strikeouts in 89 1/3 innings. However, in 2018 he is suffering from the famous sophomore slump. So far through 67 innings he has a 5.64 ERA and has struck out just 64. In 23 1/3 less innings he has surrendered 11 more earned runs and two more home runs. So what is going wrong for Castillo and can he fix it going forward?

Bad Luck

There does appear to be an element of bad luck to Castillo’s 2018 season. His ERA is higher than is FIP, xFIP and SIERA suggesting that his performances have been better than the numbers indicate. In contrast in 2017, his ERA was the lowest of the four indicating he maybe benefited from some good luck. However, in 2017 his FIP, xFIP and SIERA were 3.74, 3.41 and 3.63 respectively. In 2018, they are currently 4.89, 4.00 and 4.15 respectively. So whether or not his fortunes have reversed in this season, Castillo has simply not pitched as well in 2018.

Pitch Usage

A good place to start when working out what a pitcher is doing differently is to look at how he uses his arsenal. Castillo has used the same four pitches in 2017 and 2018, the fastball, sinker, change up and slider. However, the usage of them has changed drastically.


In 2017, this was by far the pitch Castillo relied on most, throwing it 50.4 percent of the time. In 2018 he has dropped that usage to just 35.4 percent. It is clear to see why he has cut down as his fastball was the pitch where the majority of damage was done. 1.25 percent of his fastballs in 2018 were hit for HRs, nine HRs in total. In 2018, it is still his most utilized pitch, but the damage has been less, with just 0.96 percent being hit for HRs, four HRs.


With a 15 percent drop in fastball one pitch was going to have to increase in a big way. That is the sinker which he is throwing 24.8 percent of the time compared to 11.7 percent in 2017. However, the sinker has been extremely unsuccessful for Castillo this season. 1.71 percent of his sinkers have been dispatched for HRs in 2018, compared to 0.61 percent last year. That means that already his sinker has been hit for four more HRs in 2018 than it ever was in 2017. However, he is also getting almost double the whiffs and more pop-ups in 2018 when he uses the sinker. This means that the sinker is serving as very much a risk reward pitch for Castillo this season.

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Change up

The change up is another pitch that has seen its usage increased this season, 22.7 percent to 26.1 percent. Similarly to the sinker the results with the change up have been mixed. Again, Castillo has seen an increase in whiffs on that pitch from 22.98 percent to 29.13 percent. However, he has also seen the HR percentage triple, from 0.31 to 0.97 percent. That equates to an extra two HRs on the changeup this season.


The slider has actually seen a slight decrease in usage, from 15.2 percent to 13.2 percent. It is a double whammy of bad news for Castillo’s slider. His whiffs are down over two percent when using the pitch. Additionally, after not surrendering a single HR on the slider last year he has already surrendered one this season. It is only one home run but combined with both his sinker and changeup it all adds up to bad reading for Castillo.

Batted Ball Profile

Let’s now round off by looking at the batted ball profile and how it relates to the increase in home runs for Castillo. Line drives and fly balls are both up significantly compared to last year, 7.4 and 4.7 percent respectively. That of course means that ground balls have dropped drastically, by 12.1 percent. To make matters worse Castillo’s home run to fly ball rate has increased by 2.2 percent. That can be traced back to the types of contact that Castillo is surrendering. Hard contact is up a whopping 6.7 percent on last year. To counter that both soft and medium contact numbers have dropped. With that batted ball profile it is no surprise Castillois struggling in 2018.

The Final Word

Coming into the season I was suspicious of Castillo in his sophomore season. I honestly did not expect success from Castillo last year. Making the jump from Double-A is extremely tough and often young pitchers struggle on their first exposure to the majors. However, Castillo appears to have reversed that trend and has instead struggled in year two. At this stage it is a concern but Castillo is just 156 1/3 innings into his major league career. It is expected that he will have rough stretches while he figures out what works. However, if he wants to be a top pitcher in the league he now needs to adapt and show that he can come back strong in the remainder of the 2018 season.

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