It wasn't too long ago that Starlin Castro was arguably the best hitter on the Yankees. After the team's 7-3 victory over the Royals on May 12, Castro was batting .300/.344/.483 (124 wRC+) with 8 doubles and 4 home runs in 128 PA. His 5.5% walk rate was in-line with his best seasons, and his 12.5 K% and .183 ISO would have been the best marks of his career. Sure, it was a small sample size - but nothing stood out as a tremendous outlier. His .320 BABIP was right in-line with his career norm of .319, he was hitting the ball hard to all fields, and, most importantly, he had done much of this before. It wouldn't be shocking if a 26-year-old in a new organization and lessened expectations broke out, would it?
And then the luck of the 2016 Yankees struck.
Since May 13, Castro is batting .180/.207/.303 in 92 PA. His 26.1 K% is more than ten percentage points higher than his career norm, and he now sits 142nd in the Majors in wRC+ (among 175 qualified batters). By wRC+, only Mark Teixeira has been worse than Castro over the last 30 days - but Castro also leads the team in PA in that stretch. So what happened? Is it something more than a slump, or bad luck?
One potential cause that stands out is Castro's batted ball profile. For the first five weeks of the season, Castro was spraying the ball all over the field:
Just under 39% of his batted balls went to left, a bit more than 39% went to center, and just over 22% went to the opposite field. That is no longer the case, however:
In the last three weeks, Castro has pulled the ball significantly less, and nearly 45% of his batted balls are hit up the middle. He is essentially hitting the ball in the direction of the team's top defender, which could play a role in his suppressed BABIP. He is making a bit more soft and medium contact, as classified by FanGraphs, but not to a significant degree. He is, however, hitting more ground balls, and fewer balls (as a percentage) are laving the infield.
What could have caused this? Are pitchers attacking him differently?
Through May 12, 50.22% of the pitches Castro saw were down around his knees (26.88% were just below the knees), and pitchers were trying to get him to chase pitches on the black.
Since then, 54.55% of pitches to Castro have been in that lower quadrant (33.55% just below the knees), and pitchers are avoiding that outer portion of the plate a bit more. And, lo and behold, he is swinging at those pitches below the knees more often as well:
When Castro was hitting, he was swinging at 37.2% of pitches below his knees, and 50.2% in that sweet spot altogether. Since then:
Castro has swung at 43.9% of pitches below his knees during this extended slump, and 47.7% in that area in general. And he's beating those pitches into the ground.
To be fair, this is an inexact science based upon a small sample size divided into two smaller sample sizes. But this is largely the player that frustrated Cubs fans for year - the inconsistent free-swinger that looks great when balls are dropping between infielder, but awful when he's not finding holes. And pitchers are clearly game-planning well, given his proclivity to swing at balls below the strike zone, that are far more difficult to elevate. Going forward, it will be interesting - and important - to see if Castro and the Yankees coaching staff can work in concert to make adjustments.