There’s this thing about the World Series: It’s the only baseball left. There are two teams, and they need to finish before the offseason can begin. This is the most meaningful baseball on the calendar. After all, the World Series is the whole point. So you’ve got everyone focused on at least four games — and maybe as many as seven. There are days off in the lead-up, and there are days off in the middle. During that time, almost every single thing is analyzed. Every stone in the stony field gets turned in the World Series, which is also funny because it’s one series — and it’s baseball — which means we might as well not do any analysis at all. The long and short of this paragraph is this: There’s no harm in talking about how Salvador Perez and Travis d’Arnaud receive pitches.

By the numbers at StatCorner, and by the numbers at Baseball Prospectus, d’Arnaud is a better receiver than Perez. Perez seems to be somewhere in the area of average, while d’Arnaud is one of the better receivers. I could just leave the point here, but what might be more interesting are the juicier, more granular details. Like, with hitters, you could stop at wOBA, but why not look at sub-components like walks and power? I’m going to borrow from an excellent post-ALCS article by Tom Verducci. There’s a lot in there that’s worth your time, but I’m drawing from just one section.

As you recall, the ninth inning in Game 6 was a nail-biter, and a critical plate appearance featured Wade Davis striking out Ben Revere. That plate appearance might’ve turned in the middle of the at bat, when Revere took a strike on a pitch that seemed up and away. Here’s Dayton Moore, after the fact:

“We probably got the benefit of a [strike] call on Revere,” said Royals GM Dayton Moore, referring to a 2-and-1 pitch that was high and wide but called a strike by home plate umpire Jeff Nelson. “But we’ve been known to get pitches up with [Perez] back there. We never get pitches down—because he’s so big, he blocks the umpire.”

To review, here’s Davis going 2-and-2 on Revere, instead of 3-and-1:

Everything looks so clean. You might not even realize anything’s weird until you notice Revere’s reaction. That’s the hotly disputed strike-zone call from Game 6. Here’s the hotly disputed strike-zone call from Game 5:

That time, the Royals didn’t get the call. That time, the pitch was down. You can never really distill something so complicated into a single pair of .gifs. There could be any number of reasons why one call went one way and the other went the other way. We can’t put it all on Perez. But it at least suits what Moore was talking about. We have overall framing metrics. Those are what’s most important. But different guys have different strengths and different weaknesses. Indeed, Perez scores a little better catching higher pitches than lower pitches. His World Series counterpart, d’Arnaud, scores far better catching lower pitches.

I did some messing around on Baseball Savant. I identified areas high and low, each six inches tall, in which called balls and strikes were roughly 50/50. To be precise, the high zone resulted in an average of 48% strikes, and the low zone resulted in an average of 54% strikes. I collected 2015 data for catchers who caught at least 100 called pitches in each zone. That’s not a very big sample, but I ran with it anyway. Here are the World Series catchers, when they receive pitches up in the zone.

High Zone (65 qualifying catchers)

Perez: 51% called strikes (22nd)

51% called strikes (22nd) d’Arnaud: 47% called strikes (41st)

The same catchers, receiving pitches down. This is where you see more of your “classic” pitch-framing.

Low Zone (72 qualifying catchers)

Perez: 48% called strikes (58th)

48% called strikes (58th) d’Arnaud: 68% called strikes (second)

With Perez, you see a slight preference for higher pitches. On the other hand, with d’Arnaud, you see a very strong preference for lower pitches. He was among the best low-pitch receivers in the game this year, and though some of that has to do with pitcher command, this isn’t something you fake. Let’s consider the difference between low-pitch strike rate and high-pitch strike rate. Out of 65 catchers, d’Arnaud ranks sixth-highest at 21%. Perez is toward the bottom, at -3%. He’s not the only catcher with a higher-pitch preference, but it’s quite a bit different from many of his peers.

Moore talked about Perez’s size. It’s a legitimate point; Perez is one of the biggest catchers in the game. Interestingly, he’s officially taller than d’Arnaud by only one inch, but — also officially — Perez outweighs d’Arnaud by 30 pounds. Perez does get in the way a little bit, and because he’s enormous, you can expect him to move only so gracefully. Here’s a pair of comparative screenshots, showing probably not very much at all.

Perez knows how to keep himself somewhat compact, but there are limits to how small he can get. And d’Arnaud might simply have better receiving technique. That’s not really a shot at Perez. He seems to do enough other things well, but for whatever reason or reasons, receiving isn’t a strength. He appears most comfortable catching higher pitches, and that makes you wonder about targets. At some point during his run of struggles, Johnny Cueto asked Perez if he could set a lower target, like Cueto said he was used to in Cincinnati. Whether that was something real, Perez tried to cooperate. A number of catchers will set targets below the knees. That’s not what Perez would do, so catching lower pitches forced him to move more. That movement could lead to fewer strikes, because umpires pay attention.

Maybe it’s not related to targets. Maybe it has to do with what the glove does after setting a target. Maybe it’s just the amount of motion involved in catching. Maybe it is about size and nothing else. The most likely explanation is there are multiple explanations.

Where we are is this: Travis d’Arnaud is a better receiver than Salvador Perez. Perez might have a slight edge getting strikes on pitches up in the zone, but d’Arnaud has a massive advantage down. For whatever reason or reasons, that seems to be real, so you can start anticipating where the strike-zone disputes are going to be in the World Series. Even without involving the specific umpires, you can guess that the Royals aren’t going to be thrilled with a call or three at the knees. And if there’s a close pitch up, the Royals will want it, and they might get it. There’s some chance the Royals hitters will be aggressive enough that d’Arnaud won’t have many borderline pitches to receive. But the catchers are likely to get their chances to make a difference. The Mets will take it.