It is no secret that Nick Castellanos has been struggling this year. So far, he his hitting .221/.268/.333 with only four home runs. His 63 wRC+ is the lowest on the Tigers by anyone with at least 150 plate appearances, and the ninth lowest in all of baseball among qualified hitters. While his walk rate and strikeout rate have remained consistent, his slash line is a big step backwards from last year when he was hitting .259/.306/.394 and a tick below league average with a 94 wRC+.
While the Tigers were hoping for an improvement over last year, it looks like Castellanos has hit the dreaded sophomore slump (although his defense has certainly improved). A short stint in the minor leagues is becoming more and more of a possibility.
Why is Castellanos struggling so much? Opposing pitchers may have found a weakness to Castellanos' swing and are exploiting it.
Pitchers are predominantly pitching to Castellanos low and away. One pitch that moves that way is the slider. And sure enough, according to FanGraphs pitchers are throwing 22.2 percent of sliders to Castellanos, ninth-most in baseball. According to Brooks Baseball, here is how he is hitting each pitch.
Fifty two of Castellanos' plate appearances this year have ended on a slider, and he is only hitting .154 against that pitch. Of his 62 strikeouts this season, 20 have come because of the slider, more than any other pitch. The surprising number above is that Castellanos is only hitting .169 against the four-seam fastball with 17 strikeouts. Last year, the batting average against the fourseam was at .326. What happened?
Basically, the same thing. The problem here seems to be that Castellanos is having a hard time with pitch recognition. He cannot distinguish a fastball from a slider, especially when they are in the same area of the strikezone, low and away. And the result is what we are getting, low batting averages and lots of strikeouts on those pitches (over 50 percent of his strikeouts have come on the fourseam or slider).
I'm not sure what needs to be done here in order for Castellanos to take the next step forward. Time in the minors may or may not fix this problem. One thing for certain is that Castellanos will never be the hitter we all hoped he will be if he continues to get fooled on the slider/fastball combination.