Is Nick Castellanos’ encouraging start for real?

There’s little question that Nick Castellanos looks better to the eye test than he did throughout much of 2022. The Phillies right fielder carries a .288/.367/.400 batting line through 21 games in 2023. He looks more disciplined at the plate, as he’s cut his outside the zone swing percentage to 34.8% from 43.6% last season. His nine doubles are tied for the most in baseball. Castellanos has even directly contributed to at least two wins with his baserunning. His enormous leads off third base have distracted pitchers and even drawn a balk.

However, there are still some worrying signs that his “bounce back” may be a mirage.

Castellanos finished last April strong too, as he had a .300/.374/.475 line and a .369 wOBA through 91 plate appearances across 22 games in the season’s opening weeks. As you all know, he then cratered for much of the rest of the season. This season, with 8 games left in April, Castellanos’ numbers are almost identical to last season.

• 2022: .300/.374/.475, .369 wOBA, .175 ISO, 138 wRC+, 91 plate appearances
• 2023: .288/.367/.400, .344wOBA, .113 ISO, 112 wRC+, 90 plate appearances

The eye test may say that Castellanos has looked better against the pitch that was his kryptonite last season, namely the low and away slider. In fact, he’s actually faring worse against the pitch than last season.

Castellanos hit .260 with an xSLG of .396 against sliders with a whiff percentage of 40.9% and a run value of -7 in 2022. So far in 2023, he’s hitting .111 with an xSLG of .175 and a whiff percentage of 60%. His run value against sliders is -2 and he’s seen a slider roughly 25% of the time, slightly lower than 27% last year.

Beside that alarming revelation, Castellanos is also sixth in the league with a .434 BABIP. That means an absurd number of balls he’s making contact with are finding their way into becoming hits. Last season, he carried a .326 BABIP. In his All-Star 2021 campaign, his BABIP was .340. All of this is to show that Castellanos is due a severe drop in batted ball luck. His Statcast expected numbers are all lower than his actual numbers this year and some are actually even lower than last season.

• 2022: .250 xBA, .395 xSLG, .302 xwOBA
• 2023: .239 xBA, .342 xSLG, .302 xwOBA

Despite his improved OBP, Castellanos is still striking out at a high rate. His strikeout percentage is currently at 30%, putting him in the 17th percentile among all MLB hitters. He also hasn’t hit a home run since August 27th. That’s 48 games including the postseason since the last time he put the ball over the fence. He’s never had a homer-less drought longer than 38 games in the regular season, and that one came in his first full season in the majors in 2014. In 31 regular season games since that last home run, Castellanos has a .342 slugging percentage and a paltry .081 isolated power mark.

One positive note is that Castellanos is improving against fastballs in these early stages. His .375 AVG and .325 xBA are both better than last season’s .286 and .275 marks respectively. He’s also swinging and missing at less fastballs with his whiff percentage down to 19% from 22% last season on a slight uptick in number of heaters seen.

It’s still very early in the season. Castellanos could continue to pass the surface level test while outperforming his peripherals. Or he could even just improve overall and bring his underlying numbers to a healthier spot. But it would appear he is due for some strong regression sooner rather than later.