Are the Reds seeing a new and improved Luis Castillo?

Luis Castillo threw a complete game 2-hit, 1-run game this weekend in a win over the St. Louis Cardinals. During the game, and even after the game I saw plenty of posts on twitter about how Castillo was back, or how long it’s been since “we’ve seen this version of Castillo” – and of course when a player has a big game you’re going to see those kinds of reactions. But it also got my brain wondering: Is he back? Is he different? What’s going on here?

Luis Castillo was acquired prior to the 2017 season from the Miami Marlins in the Dan Straily deal. After spending most of the first half of the season in Double-A Pensacola, the Reds made the decision to call up the right-handed starter without having any experience at Triple-A and insert him right into the Major League rotation. It was a moved that looked brilliant. Castillo made 15 stars the rest of the way and the 24-year-old posted a 3.12 ERA with 98 strikeouts in 89.1 innings. There was nothing in his stats that was an obvious sign that he was getting by on luck – his walk rate was solid, he was keeping the baseball in the ballpark, he had big ground ball rates, and he was missing tons of bats.

Big expectations were understandably there for 2018. Luis Castillo was coming off of a big rookie season and the Reds finally had a young pitcher in “the rebuild” who had come into the big leagues and held up their end of the bargain as a starter for more than a few starts. But things were tough for Castillo in the first half of 2018. He made 20 starts and posted a 5.49 ERA before the All-Star break. His home run rate was high, his strikeout rate was good – but down from the year before – and his ground ball rate was down significantly.

Things changed in the second half. He made 11 starts after the All-Star game and saw his ground ball rate come up – though at 48% it was still far lower than the year before, his home run rate dropped off, his strikeout rate jumped up, and his walk rate fell. That all led to an ERA of 2.44 in the second half.

The first half of 2019 saw Luis Castillo dominate in terms of ERA, posting a 2.29 mark in 18 starts. He posted a good home run rate, and his strikeout rate remained high – and his ground ball rate returned to where it had been in 2017, near the top of the MLB leaderboards at 56%. But his walk rate was high in the first half. In the second half of the season things got strange. His walk rate dropped off, his strikeout rate remained the same, his ground ball rate remained the same, but his left on base rate and BABIP both took big turns in the opposite direction from where they were in the first half and led to an ERA of 4.78 over his 14 starts.

The career for Luis Castillo has been rather short to this point – but he’s been a bit up-and-down in each half since he debuted. He’s gone through stretches where he’s dominated – three different half-seasons, but he’s also had two different half-seasons where he’s struggled to keep runs off of the board.

The 2020 season is not even the length of a normal “half”. While realistically the half-way point of a season is the 81st game, the All-Star game always falls beyond that point in today’s game. Still, it’s not usually falling after game 102, either.

After this weekend, Luis Castillo’s ERA sits at 3.44 on the season through nine starts. He’s rocking a career best 59.1% ground ball rate (just ahead of his 58.8% rate from 2017 – and his current rate is also leading Major League Baseball among qualified starters). His strikeout rate of 29.5% is also the best of his career. His home runs allowed per 9-innings pitched is easily the best rate of his career, as is his home runs allowed per fly ball rate.

The 2020 season, in terms of ERA, is right in line with the totality of 2017 and 2019 when he posted a 3.12 and a 3.40 ERA. Once we adjust for the ballparks pitched in, and the league as a whole, his ERA+ is 144 – that’s the same as it was in 2017 and a little better than it was in 2019 (when it was 139). On that front, he’s not really any different from the past version of himself.

But there are definitely some differences from the 2020 version of Luis Castillo. For three years running we saw Luis Castillo have arguably the best change up in baseball. And the numbers back that up, too. From 2017-2019 Castillo’s change up rated out as the most effective change up in baseball per-100 change ups thrown according to Fangraphs at 2.33 runs better than average per-100. That was tied with Zack Greinke. Only Hyun-Jin Ryu was also above the 2.00 runs mark over that span among the 92 pitchers that qualified for the list and threw a change up at least 5% of the time in that span. It was a pitch that he dominated with.

In 2020 that simply has not been the case, or anywhere near it. This season Luis Castillo’s change up value per-100 is just 0.06. It’s basically been a league average change up. Among the 84 pitchers who have thrown 30 innings this season and a change up at least 5% of the time, Luis Castillo’s change up has been the 51st most valuable change up. You could have won a lot of money making a bet on a stat like that before the season began.

Despite having elite velocity – Castillo’s fastball is 3rd among pitchers with 30 innings, trailing just Dustin May and Jacob deGrom this season – his fastball doesn’t grade out all that well, basically coming in as a league average offering in terms of results.

This year it’s been his slider that’s been the real difference maker. That’s a pitch that was dominant in his rookie season – grading out as 2.13 runs above-average per-100 thrown that season. But it’s been a league average in both 2018 and 2019. This season it’s back to being an above-average offering, though not where it was as a rookie. It currently has a 0.70 value per-100 thrown. It’s not an elite pitch, but it’s an above-average one that’s been his best offering so far this season by a wide margin.

So getting back to some of the thoughts from the top of this article…. is Luis Castillo back? Well, I really don’t know. Was Luis Castillo really gone? He’s been up-and-down for long stretches throughout his career. Right now he’s back in a good run of things, but this season has seen him make just nine starts. Some of them have been outstanding. A few of them have seen him struggle a little bit.

That said, it has been a long time since we last saw this kind of 9-game run by Luis Castillo. Part of that is because there wasn’t baseball played in April. Or May. Or June. And most of July was without baseball, too. From June 22nd to August 11th of 2019 Luis Castillo had a run pretty similar to this current stretch. His ERA was 3.38 (nearly identical) over 56.0 innings with 17 walks and 69 strikeouts. There were eight starts after that to end the season, and they weren’t great as Castillo posted a 5.55 ERA in that span, and really helped forget the good stretch that came before that.

Is he different? Yes, he is. The decline of the change up has been a shocker. Not that it’s a bad pitch, really, but it’s just merely average this year. The slider has taken big steps forward after being merely average for years. And his home run rate is also far and away at the lowest point of his career. From 2017-2019 his HR/FB rate was between 17.2%-17.9%, while this season it’s at 12.1%.

This was a lot of words for me to come to the conclusion that, yes, Luis Castillo is a little bit different in 2020 than he has been in the past. But that I also don’t really know if he’s back or if he was ever really gone, either. I’m not sure if he’s “new and improved”, but perhaps he’s a little different. What I do know is that Castillo’s pitching well in 2020 for the Cincinnati Reds and he’s getting it done a little differently, but a little bit the same as he has in the past when he’s also pitched well. He’s been overshadowed a little bit this season with what Trevor Bauer’s been doing, and by what Sonny Gray had been doing before his last two starts (and before he hit the injured list this weekend).