Nick Castellanos has emerged as one of this year’s top trade deadline targets, thanks to his low cost (a reported four million dollars over the rest of the season) and strong bat (115 wRC+ to date). He’s played exclusively right field for the Tigers in 2019, and while that doesn’t mean he can’t play elsewhere, he’s probably going to be in the corner outfield.
Castellanos is a favorite request from Cubs fans of their front office. And fairly so. Albert Almora Jr. has struggled mightily at the plate this year (67 wRC+ to date), and even if he hadn’t, every above-average bat is valuable.
But how valuable, exactly, would Castellanos be on the Cubs? In other words, how much better would the Cubs be over the remainder of 2019 if they were to add Castellanos?
Statistics available on FanGraphs can help us answer that, but we’re going to have to establish some parameters.
First, you should know that at a very rough level, every additional run a player is worth—whether on the mound, at the plate, in the field, or on the bases—compared to another player is equivalent to roughly one tenth of a win.
Second, we have to acknowledge that the ripple effect of adding Castellanos to the Cubs’ roster is more nuanced and far-reaching than we can adequately evaluate. To keep ourselves from scrapping over fractions of fractions, we’ll make the following assumption: If Castellanos were added, he’d become the everyday right fielder and Jason Heyward would replace Almora as the everyday center fielder. We’ll say that this would happen in 75% of the rest of the season to reflect late-inning defensive replacements, off days, and the whims of chance/matchups.
Third, we have no idea how chemistry would be affected by such a move, or who the Cubs would give away to create roster space. Because we don’t know these variables, we’ll ignore them, and hope the latter is captured in that remaining 25% from the previous paragraph.
Now, how much is Castellanos worth:
Castellanos’ UZR/150 this year is -6.5, meaning that over an entire season, he’d be six and a half runs worse defensively than an average right fielder. Over 409 plate appearances thus far, he’s been 9.4 runs better than an average right fielder at the plate and on the bases. With about 35% of the season remaining, and our 75% assumption, Castellanos would therefore be expected to put up about a quarter of a season as the Cubs right fielder, getting approximately 180 plate appearances. After running the numbers, this comes out to a combined 2.6 runs above average as a right fielder.
Jason Heyward’s offensive production should remain the same, and we’re going to say his value will as well. There are probably differences between right fielders and center fielders in terms of the averages against which they’re evaluated on the base paths and at the plate, but those differences should work in opposite directions to one another (center fielders are likely worse at the plate but better on the base paths), and in a quarter-season sample, they’re likely small, so we’ll call it a wash for Heyward, with a bigger risk of understating his value (and therefore the Cubs’ improvement) than overstating it. Defensively, though, Heyward will become less valuable, because the difference between his 10.3 UZR/150 in right and his -22.6 UZR/150 in center comes out to him being 8.2 runs less valuable over the remainder of the season in such a scenario.
For Almora, the Cubs would lose his 7.1 UZR/150 in center but would also lose the 14.3 runs worse he’s been than an average center fielder over his 295 plate appearances in 2019. In total, that’s a player who’d be 7.1 runs less valuable than an average center fielder over the quarter-season we’re projecting.
Overall, this math says the Cubs would net a 9.7 run improvement from switching out Almora for Castellanos—an entire win. But the corresponding 8.2-run decrease in Heyward’s value means they’d actually only be 1.5 runs better in total, a much smaller increase (though not meaningless—remember last year?).
There are a few complicating factors, though.
For one thing, Heyward has been significantly worse in center field this year than ever before. If you average his season UZR/150’s in center field since joining the Cubs, and weight that average by innings played in each season, the number you get is -2.3, 20 runs better than his season-to-date UZR/150, so five runs better over the course of a quarter-season. That’s a half-win difference, over just 40 games.
Another is that Almora has measured out better defensively this year than ever before. His 2018 UZR/150 in center was more than four runs poorer than this season’s. The sample size on his individual seasons is larger than Heyward’s, and therefore more deserving of confidence, and he’s on the opposite side of the aging curve from his teammate, making it more likely he’s getting better than worse defensively, and more likely Heyward’s getting worse defensively than better.
There’s also the matter of Almora’s offense, which is markedly worse this year but also comes on the back of a .258 BABIP that’s in turn much worse than his .316 career BABIP. It’s possible Almora’s had some bad luck at the plate.
Even with all this uncertainty, we can take away the following:
- It’s unlikely the Cubs would be worse with Heyward and Castellanos in center and right instead of Almora and Heyward.
- The Cubs might be as much as a win better over the rest of the season in the Castellanos arrangement.
- The Cubs would have a marginally better chance in the playoffs with Castellanos on the roster, and margins matter.
Still, the question will remain whether Castellanos is worth the cost—not the four million dollars, but the prospects or young talent with which the Cubs would have to part to acquire him, which may be higher than it would have been in last year’s market because of a thinner crop of good bats. If the goal is to maximize the total number of championships, the math has to span more than just 40 games. And while we don’t do that math, and nobody can figure out the perfect equations to account for all of it, the Cubs’ front office is likely doing those kinds of evaluations. The question is whether their goal is to maximize championships in the long run, chase one right now, compete consistently for them, or something else entirely. And the other question is the budget with which they’re working.
We’ll see.
