Nick Castellanos Is the Hottest Hitter in Baseball

This is Sara’s first piece as a FanGraphs contributor. She has been writing about baseball on and off since her byline first appeared in her local paper at age 13. Her work has appeared at Baseball Prospectus, where she contributed to Short Relief, and as a lead voice covering the Chicago Cubs for SBNation’s Bleed Cubbie Blue, where she also co-hosts their podcast, Cuppa Cubbie Blue. She’s a fan of advanced metrics, keeping score by hand, and bat flips. Sara is a meticulous researcher who applies that talent to all parts of baseball, from big issues like labor relations to idiosyncratic issues like Javier Báez and his uncanny ability to deliver on an 0-2 count in 2019. She looks forward to bringing her research skills to FanGraphs, which has long been her first stop for data to support her writing.

Most of the talk around Nick Castellanos to start the 2021 season has focused on his two-game suspension for his role in the events preceding the benches clearing between the Reds and the Cardinals during their second game of the season:

But while baseball fans and analysts argue about whether Jake Woodford intentionally hit Castellanos as retaliation for his hop, skip and bat flip after his Opening Day home run the game before, or whether Yadier Molina’s instinct to protect Woodford was also worthy of a suspension, I want to focus on Castellanos’ red hot start to 2021. It turns out the Reds outfielder has had a lot to celebrate one week into the season.

To be clear, every small sample caveat in the universe applies to this run. A .435/.480/1.130 line and 317 wRC+ is unsustainable over the course of a season. But there is always some magic in the first week or two of the season, and it’s entertaining to take a closer look at the numbers. And while what Yermín Mercedes and Akil Baddoo have shown in their early big league action has been fun to watch, it’s in a slightly different category from what an established player like Castellanos is doing.

Castellanos boasts a career 112 wRC+. Yet, despite a similarly hot start to his 2020 season powered by a 12-game hitting streak, there was real cause for concern that he had taken a step back by the end of the season. The .225/.298/.486 line and 102 wRC+ Castellanos put up during 2020 were quite the outliers relative to his career marks, as was his 28.5% strikeout rate. As his numbers tapered off, Castellanos admitted he started pressing more down the stretch as the end of the shortened season loomed:

“Usually those little spells where nothing’s falling are easy to ignore, but then when you look up and you only have 17 games left, you know?” Castellanos said. “To say that I didn’t pay attention to it or I wanted to do really well? Or I tried to do too much? I’d be lying.”

But the peripherals around that slump indicate Castellanos may have been in the midst of some bad luck. He posted a career-low BABIP (.257) during the pandemic shortened season, while his .329 wOBA was outstripped by his .372 xwOBA, and his xSLG (.539) based on the quality of his contact was significantly higher than than his SLG; his 16% barrel rate was a career high, and good for the 95th percentile in all of baseball. It all combines to make 2020 seem like a probable blip in an otherwise successful career at the plate, with Castellanos poised for a 2021 bounce back.

So just how well has that bounce back gone so far? To put it simply, through one week of baseball in 2021, Castellanos is in the top 1%.

I wanted to compare Castellanos’ 2021 start to other players’ first weeks in recent seasons. To do that, I pulled offensive stats for the first week of the last five seasons for players who had at least 20 plate appearances. Here are the top 20 first week starts since 2017, sorted by wRC+:

There is a lot of noise in this data and the first week is not a crystal ball for what will happen over the next 150ish games. As you can see above, during his first week with the Phillies, Bryce Harper he might be in line for another MVP campaign. His pace slowed down, and he wound up “settling” for a .260/.372/.510 line on his way to 35 home runs, a 125 wRC+ and 4.6 WAR. It was a lovely season, and certainly among the top five campaigns of his career, but it wasn’t the MVP-caliber season the first week suggested. At the other end of the spectrum, Harper’s 2019 teammate Maikel Franco saw his red hot start to that season come to a screeching halt; he finished the year with a .234/.297/.409 line and a 70 wRC+, which was the seventh worst wRC+ in baseball among batters with at least 400 plate appearances.

The fate of 2021 Nick Castellanos probably lies somewhere between Harper’s 4.6 WAR season and Franco plummeting back to Earth. Castellanos still has to play the field, a fact that is likely to suppress his overall production. He’s unlikely to stay in the top 1% of the league by xSLG, just as he’ll likely strike out more than 8% of the time. Yet, if he can sustain the career high barrel rates and average exit velocity he demonstrated in 2020 despite an underwhelming line, it could go a long way to curing the Reds’ offensive woes (their 91 wRC+ ranked 22nd in baseball last season) and give him plenty more opportunities to flex at home plate.