The Sean Casey Effect: Delving into the new hitting coach’s true impact

With the Yankees offense scuffling throughout the second half of the 2022 season and first half of 2023, general manager Brian Cashman took the unprecedented step of firing hitting coach Dillon Lawson during the All-Star break and hiring MLB Network analyst/ex-player Sean Casey to replace him. The message was clear: the lineup, which had posted a 96 wRC+ and ranked 19th in runs scored at the halfway point, had not been good enough. Obviously, the organization hoped that a new voice, a veteran voice, would be able to have an effect.

The change was immediately invisible. Aside from an increase in walk rate that sparked an increase in on-base percentage — the result of a focus on patience at the plate, the antithesis of Lawson’s aggressive “hit strikes hard” mentality — the Yankees offense actually saw a dip in performance from the first half to the second.

From this data, the conclusion is simple and self-evident: Sean Casey is not the answer. Given the social media reactions to premature reports that the Bombers had offered him a contract for next season, it’s clear that many fans would agree with this assessment.

But is Casey truly to blame? Or did something else cause the already-poor Yankees lineup to regress in the second half? Let’s start by looking at the raw data of first half and second half performances, listed below (each chart is organized by number of plate appearances, minimum 50):

First Half

Second Half

From this data, we can divide the players into four categories:

1. Core veterans still under contract for 2023 (Aaron Judge, Gleyber Torres, DJ LeMahieu, Giancarlo Stanton, Anthony Rizzo, Jose Trevino, Kyle Higashioka)
2. Rookies (Anthony Volpe, Oswald Peraza, Oswaldo Cabrera, Everson Pereira, Esteval Florial, Austin Wells; NOTE - Jasson Domínguez only had 33 plate appearances, and did not qualify for this list)
3. Non-tender candidates (Jake Bauers, Ben Rortvedt, Billy McKinney, Franchy Cordero)
4. Free agents/players who already left (Harrison Bader, Isiah Kiner-Falefa, Willie Calhoun, Aaron Hicks, Josh Donaldson)

Obviously, these categories are not foolproof — for example, Higashioka is currently under contract for 2023, but it would not be a surprise if they trade him because he’s behind both Trevino and Wells — but for our purposes, they’re a good approximation.

Let’s start with the veterans under contract:

The trend here is clear: when we remove Rizzo, who was dealing with concussion symptoms and had a reaction time slower than you and me at the plate, the Yankees veterans were much better in the second half. A large portion of this uptick in performance came from Gleyber Torres and DJ LeMahieu, who looked much like their 2019 selves in July, August, and September.

The only two healthy starters who did not see an increase in performance were Judge, who still posted a ludicrous 164 wRC+ even though he technically wasn’t completely healthy to begin, and Stanton. The big righty struggled throughout the season, and Casey mentioned after the season that he needs to “Start from the ground up” and rework his “careful” swing to tap into his athleticism more.

Unfortunately, Casey wasn’t quite as successful with the rookies and journeymen/washed up veterans:

It’s hard, to make an accurate assessment of Casey in these two categories. On the one hand, both Volpe’s and Cabrera’s numbers are lackluster in the second half. Cabrera, however, did hit well when used exclusively as a role player in July and August, and only slumped to the extent he did in the first half when he returned to a full-time role at the end of September. Volpe, meanwhile, had a hot August at the plate before tapering off in September; perhaps this was the result of fatigue, as he never played more than 130 games in a season before playing in 159 this year. The other rookies struggled making the adjustment to the Majors, which is not all that unusual; it’s hard to blame Casey for their performance, just as it would be hard to praise him if they all came out mashing like Domínguez did.

As for the journeyman veterans ... many of them were playing above their career norms in the first half, and regressed hard in the second half. While it’s possible that Lawson was doing something differently that allowed them to perform better at the plate which Casey did not replicate, it’s also likely that they got exposed. None of them belong in everyday roles, with the exception of Harrison Bader, and that’s exclusively due to his elite glove.

Altogether, this data shows that any analysis of Sean Casey’s performance as hitting coach requires more thought than simply looking at the team’s overall stats. Under his guidance, two important veterans put together their best stretch at the plate in years (particularly Torres). Ultimately, journeymen and rookies dragged down his overall numbers, both of which were the result of poor roster construction. The journeymen played as much as they did because the front office opted to end the season thin in the outfield and reliant on multiple injury-prone players, and the rookies played as much as they did because the journeymen were unable to keep the Yankees in postseason contention. The amount of playing time each group received should not be held against Casey.

At this point, I’m not completely sold on Casey as the Yankees hitting coach for 2024, but I’m also not out on him either. While, in my opinion, the organization should at the very least promote an assistant or two from the minor leagues who are familiar with the rookies, there’s no route they could take this winter that would get me worked up.

October 25th update: Sean Casey announced that he will not return as hitting coach in 2024.