MJ Melendez has done the impossible on defense

His improvement has been nearly unbelievable

Of the group of young Royals hitters who made their debuts over the last few years, none has perhaps been as tantalizing and as frustrating to watch as MJ Melendez. This has been true at the plate, where he’s shown rare power and plate discipline alongside contact issues and long slumps. It’s also been true on defense, where Melendez’s clear athleticism has not translated to good defensive numbers anywhere on the diamond.

Melendez was drafted as a catcher, spent nearly all of his minor league career as a catcher, and mostly played catcher in his debut season of 2022. But the Royals moved him off catcher because it was apparent that his defense was not acceptable there. Among the 67 catchers who accumulated 500 or more innings behind the dish between 2022 and 2023, Melendez ranked dead last in Defensive Runs Saved (DRS) per inning played and second to last in framing runs per inning played.

As a result, the Royals rather quickly moved him to the outfield. Melendez then proved to be almost as bad there. Among the 98 players who accumulated 1000 or more outfield innings between 2022 and 2023, Melendez ranked fourth worst in DRS per inning played, 10th worst in Statcast Fielding Runs Above Average (FRV) per inning played, and 18th worst in Ultimate Zone Rating (UZR) per inning played.

So it has been a rather pleasant surprise this year that Melendez has been legitimately good out there in left field. It has been very enjoyable to see!

If you’ve ever read me talk about defense, you’ve seen me use my pet stats AVGDEF and AVGDEF/1000. Before getting into Melendez’s numbers, a quick recap: since defense is harder to measure and since DRS, UZR, and FRV measure and value defensive components slightly differently, there is sometimes discrepancies between them. Fortunately, they all share the same scale—runs above or below league average—and the average of the three is AVGDEF. By prorating it to 1000 innings, you can turn defense from a simple counting stat to a rate stat, which is better for comparing across players with different innings counts.

And no matter how you cut it, Melendez’s improvement between last year and this year is almost unbelievable. The stats say that MJ has gone from one of the worst outfield defenders to one of the best outfield defenders.

The most important number here is 19.7, which is how many runs better per 1000 innings Melendez has been in the outfield this year versus last year. For reference, +20 runs over the course of the year is just about the difference between Lorenzo Cain patrolling center field at the height of his athletic powers and the average outfield defender. It’s gigantic.

How, then, is Melendez doing this? The biggest single improvement that’s happened has been in what Statcast calls “outfield jump.” Jump calculates feet covered in the correct direction within three seconds, combining reaction speed, initial burst, and route efficiency. By that metric, in 2023 Melendez averaged 31.1 feet covered, or -2.3 feet versus league average. In 2024, Melendez is averaging 32.9 feet covered, or -.1.5 feet versus league average. Additionally, Statcast is tracking Melendez as being slightly faster than last year.

That seems like small potatoes, but is has contributed to Melendez’s range factor being much better. Again per Statcast, Melendez’s range was in the second percentile last year and is in the 69th percentile this year. Finally, Melendez is using his cannon arm to an even bigger extent this year and getting even more value out of said cannon.

So, overall, Melendez is reacting better on fly balls, he’s covering more ground, and he’s using his arm to its fullest extent. That’s a pretty good recipe for success. But it’s also just amazing that he’s done so at all. In October of 2022, I looked at other catchers who made the full-time jump to a non-first base position after debuting as a catcher. There just aren’t a lot of examples. As I concluded:

It would not be a mistake to claim that Melendez must thread a needle here, especially if he wants to become an impact player and not just a serviceable big league regular: he needs to become a much better defender and a better hitter. Do one or the other, and the Royals will have a perfectly nice player. Do both, and Melendez might just become a star. As history has shown us, though, catcher specialization is a double-edged sword.

Small sample size this year, sure, but Melendez has done a lot to solve the defensive component. It’s borne out in the stats, as Melendez has been nearly as valuable per Wins Above Replacement as he was last year in a quarter of the playing time. Ultimately, Melendez’s bat needs to improve for him to stay around as an impact player. But as a good corner outfielder, Melendez doesn’t have as far to go in order to be a good player, which is definitely a nice development for Kansas City.