By: Chris Larson
Luis Castillo has been an integral part of the Cincinnati Reds starting rotation so far this year and a big reason why the Reds starting rotation leads the National League in ERA (3.36) entering play on Tuesday. In addition to leading the National League in ERA, the Reds starting rotation ranks fourth with an overall strikeouts-per-9 rate of (9.84) and lead the National League with a cumulative Opponent Batting Average Against of (.221) heading into play on Tuesday.
Without Luis Castillo, the Cincinnati Reds starting rotation would not be what it is and certainly would not be nearly as successful as it has been to this point. Simply put, Castillo has started to emerge as Cincinnati's future ace and a true household staple at the top of the starting rotation that the Reds can build around moving forward, but where did he come from and what exactly is making him break out this season?
Well, to start out with, Luis Castillo, who turned 26 years old last December and is right in the midst of his peak, was born in the Dominican Republic and made his official MLB debut on June 23rd, 2017 against the Washington Nationals. During his debut, Castillo pitched 5 innings, while surrendering 5 hits, 5 walks, and recording 5 strikeouts. Castillo made such a big impression that his name quickly floated out as being an available starting pitcher on the market, later on that same season, in July.
If you recall, the San Diego Padres had a trade set up with the Cincinnati Reds to acquire Luis Castillo for Colin Rea, but the deal was later nixed because of a medical issue surrounding Rea. Just imagine how powerful the San Diego Padres starting rotation would be with Chris Paddack and Luis Castillo at the top anchoring things down. Rather, the Cincinnati Reds will now get to enjoy him through at least the 2024 regular season.
Castillo ended up finishing his rookie season in 2017 with a 3.12 ERA over 89.1 innings of work, a 3.74 FIP, and 98 strikeouts. Regarding this season, Luis Castillo has a 1.97 ERA over 50.1 innings pitched with an ERA+ of (232) and an overall strikeouts-per-9 rate of (10.5) so far. Certainly more promising than his rookie season indicated and a significant credit to the development that Castillo has undergone as well as the contributions by new Cincinnati Reds pitching Coach, Derek Johnson, who was formerly the pitching coach for the Milwaukee Brewers.
Outside of his ERA, has a (1.4) WAR, (.243) BABIP, a (85.8) left on-base percentage, and an Opponent Batting Average Against of (.173) to this point this season. It's not necessarily those statistics that have made Luis Castillo an entirely new pitcher, but rather his repertoire of pitches that he is relying on more than ever this season. Here is a chart showcasing Castillo's pitch types, dating back to 2017, when he first debuted in the big leagues, courtesy of data obtained by FanGraphs.
As you can see from the chart, he is relying much less on his fastball, more on his sinker now compared to his rookie season in 2017, about 10% more on his changeup now compared to his first season in the league, and a little less on his slider. What's interesting is that many teams discourage pitchers from throwing a sinker anymore and that's one reason why free agent starting pitcher, Dallas Keuchel, likely remains out on the open market without a team. Some teams might be hesitant to sign Keuchel because of his reliance on that, but that certainly shouldn't matter because as is the case with Castillo, it's a pitch that is his bread and butter and something that has vastly contributed to his overall breakout this year.
Furthermore, the overall contact rates and where the ball travels when it is hit, have changed over the past three seasons for Castillo as well. Take a look at the chart below for more information regarding both of those things, courtesy of FanGraphs.
From this chart, it can be gathered that Luis Castillo is throwing his pitches in a location where they are pulling less, traveling more to center, and finding their way out to the opposite field less often. In addition to all of that, it is obvious that Castillo is inducing less soft contact and more medium level contact, but has found the perfect ingredients to prevent his pitches from racking up a lot of hard contact against the opposing teams pitchers.
Essentially, with a mix of throwing his pitches in the right location, a slight uptick in velocity on a few of his pitches, and the knowledge of pitching coach, Derek Johnson, Luis Castillo has been able to mix all of those things together and decode the recipe for success. For more on the velocity of his pitches, take a look at another chart below, courtesy of FanGraphs. (All values represented below in MPH - Miles Per Hour).
Based on this chart, you can start to infer that some of the increase in his overall medium contact rates could be based off of the slight uptick (1.7 MPH) on his slider pitch this season compared to last and potentially the little increase on the other two pitches as well (0.2 MPH on the fastball and 0.7 MPH on the changeup). However, more goes into the equation depending on the ballpark, the strength of the opposing team's batters, and the overall environmental influences as well, which is a discussion for another day because it would be way too long to list all of it out here!
Finally, to wrap up the discussion and try to pinpoint what is contributing to the breakout of Luis Castillo this year, lets take a look at a heat map comparing his pitches and location from last season versus this season so far.
The top photo shows the Opponent Batting Average Against for the 2018 regular season, while the bottom showcases the Opponent Batting Average Against for this year. Of course, you have to remember that the sample size is much smaller for this season since it only accounts for 8 starts, but it gives a good indication as to where Castillo is experiencing the most success and where he might end up getting batted around more.
What's interesting in these two graphics is the stark difference in where Castillo is throwing his pitches. As you can see from the top graphic from last season, all nine of the squares in the strike zone are colored, while only six of the squares for this season are colored. That means that Castillo has figured out that if he throws his pitches at belt level or lower to the opposing team's hitters, he will likely experience more success and be able to rack up those strikeouts.
Beyond that from a location aspect, Castillo got hit around a lot in the upper part of the strike zone, as well as outside of the zone last season, but since he isn't throwing his pitches in those areas as much this year, things look reverse. Rather, he is getting hit hard directly in the middle of the strike zone (like any pitcher probably would) and down in the lower right corner. It will be interesting to look at these two charts come the end of the season and see if opposing teams picked up on the location of his pitches and made the necessary adjustments.
Regardless, Luis Castillo has shown many signs of being in the midst of a true breakout season and has truly emerged as someone that the Cincinnati Reds can have as a pillar at the top of their starting rotation for years to come. For now, Castillo needs to continue to focus on mixing together all of the ingredients mentioned above, along with the advice of pitching coach Derek Johnson, to continue to experience success and show everyone how smart the Reds were when they decided to hang onto him almost two years ago.
It's no guarantee that all of this will lead to Castillo being mentioned in the conversation for the NL Cy Young Award, but if this all continues, you would have to think that he would be a legitimate option to win the award or at least finish in the Top Three.