Gerardo Parra reached base only one time in the World Series, a walk against Josh James in Game 4. It wasn’t a key moment in the series — the Nationals were down 4-0, and while Parra scored, the Nats lost 8-1. When he reached first base, he was downright businesslike:

But businesslike isn’t normally a good description of Parra’s time on the Nationals. He’s widely regarded as a great clubhouse guy, ambushing Stephen Strasburg with hugs and keeping things light over the long grind of a season. He also, you may have heard, uses “Baby Shark” as his walkup music, a song that Nationals fans and players alike have rallied around.

If you’re curious, here’s a handy guide of the hand signals the Nationals make after hits:

??? here's a handy "Baby Shark" guide featuring various members of the shark family: pic.twitter.com/5miR3Yyobc — Post Sports (@PostSports) October 26, 2019

Walks aren’t included, so Parra didn’t celebrate when he reached first. But the rest of the team stuck to the script. When Victor Robles singled in the eighth inning of the same game, now an 8-1 affair, he fit a tiny shark into his various post-hit gestures:

But the shark was perfunctory. And that led the crack FanGraphs editorial staff, the same one that brought you such articles as “Let’s Use Reason to Deduce When Archie Bradley Pooped Himself” and “A Taxonomy of Striking Out Against a Position Player Pitching”, to wonder: are the sharks influenced by leverage? And if they aren’t, should they be?

A reasonable prior expectation is that the hand gestures aren’t influenced by how important the play is. There’s that Washington Post guide, after all, which strictly delineates the sharks by hit type. Robles brought out a baby shark even though he might prefer to just carry on with his business, perhaps with a tiny amount of pointing up. And observe Howie Kendrick, under the watchful eye of the dugout shark coordinator, throw up a mommy shark after a double, up 7-1 on the Cardinals:

But those two sharks only show half the picture. Did Kendrick even want to do a shark there, or was he being coerced? Observe Kendrick’s face as he sharks:

One needn’t be a body language expert to see that Kendrick’s heart wasn’t in it. Ryan Zimmerman singled Kendrick in, and seemed to provide a counterpoint to Kendrick’s stoicism:

But watch that play closely, and it’s hard to tell how committed Zimmerman is to the baby shark. He’s at a fever pitch when high-fiving the first base coach, but the shark seems performative, aimed at appeasing Parra.

There was only one way to settle it. I had to watch the highest-WPA plays of Washington’s postseason run and measure the excitement behind the sharks. How else could we get to the bottom of this, the most important mystery of the Nationals’ glorious playoff run?

Let’s start at the top, with the single most game-swinging play the Nationals had all October, Juan Soto’s three-run single against Josh Hader. Soto’s celebration was joyous, carefree — and, as far as I can tell, also shark-free. Rather than wonder whether to do a baby or mommy shark (more on this later), Soto settled for pure effervescence. And Parra? He was celebrating right along with Soto:

The second-biggest play for the Nationals is no help: Kendrick’s two-run homer off of Will Harris swung the World Series, but it was a home run, and we all know that home runs lead to dugout dance parties rather than sharks of any persuasion. The third-biggest play, too, was a home run; Soto’s equalizer against Clayton Kershaw in NLDS Game 5. But we can zoom in on another important Soto play:

This was the aftermath of the two-run double against Gerrit Cole that provided the winning margin in Game 1 of the World Series. That’s an amped-up mommy shark: four shark bites, a big grin, and a few points upwards. Not only did he manage more bites than Kendrick’s half-hearted appeasement of Aníbal Sánchez, he did it with great gusto.

But Soto isn’t the ideal subject on which to base our unified theory of shark gestures. He’s so happy, so lovable, so in the moment that he doesn’t represent the Nationals as a whole. Juan Soto dances after taking a pitch. He’s probably not the right person to watch when you want to measure a change in happiness based on how important a moment is.

Let’s turn instead to what seems like a great defeat for the leverage-based-shark theory: Howie Kendrick’s single off of Ryan Pressly in Game 2 of the World Series. It was a huge play, doubling the Nats’ lead and leaving the bases loaded, and he stone-faced it:

But that leaves out context, and this investigation is nothing if not nuanced. Kendrick couldn’t be sure that play would be scored a hit; in fact, it probably should have been scored an error. A baby shark without a hit is a no-no, and so Kendrick reacted appropriately. If the official scorer had settled the matter more quickly, I’m sure Kendrick would have mustered a few bites.

Indeed, Asdrúbal Cabrera was next up, and his single, while less important than Kendrick’s, was still momentous. And while there’s no video evidence of Cabrera representing Baby Shark, no less than Stephen Strasburg, a man so stoic Gerardo Parra made it his personal mission to hug him, got in on the act:

And when Ryan Zimmerman followed with a single of his own and reached second on an error, he was caught up in the rapture, using a doubles-only hand gesture to celebrate something that was undoubtedly not a double:

Getting too excited to remember the shark rules? Sounds to me like someone is letting the moment get to them.

In fact, there’s evidence of the moment influencing the shark everywhere you look. Remember Robles hurrying his way through a celebration in a blowout? Watch him here, after a high-leverage single that preceded Soto’s double in the World Series:

Or heck, watch Zimmerman tell a whole story with his cat-who-ate-the-canary grin as he shrugs and sharks all at once after a broken-bat single off of Hader:

And what article about the Nationals would be complete without a demonstration of daddy shark? Robles got the dugout in a tizzy with a high-leverage triple in Game 3, and if this doesn’t show the importance of context on shark gesturing, I don’t know what does:

With this investigation now concluded, allow me to present a unified theory of baby shark. First, there’s troubling inconsistency around baby shark and mommy shark. When a player reaches second base, whether on a double or a single plus an error, there appears to be a norm towards using mommy shark — witness Zimmerman and most of the dugout agreeing in real time on mommy shark after Bregman’s error.

The rules around first base are in opposition to second base. Walks don’t elicit a baby shark, although they entail reaching first base safely, just as a single and an error lead one to second base without pester. Reaching first base on an error doesn’t even entitle a Nationals hitter to a baby shark, though clearly the error can upgrade a baby shark into a mommy shark. There’s chaos here, in other words. Would a single and a two-base error lead to a daddy shark? Would a player thrown out trying to stretch a single into a double still show baby shark? Questions abound.

But for whatever confusion there is around which shark to use (or, in Soto’s case, whether to use a shark at all), there’s no doubt around the influence of leverage on shark celebrations. The shark form is wide and varied: you can be Kendrick, stone-faced and brief, or you can be Strasburg, elated and at length. And nothing predicts the energy put into the shark better than the situation that led up to a sharking.

Want to shark correctly? Pay attention to leverage. Is it a big play? Are emotions running high? Shark with your whole heart. Have fun with it, really go wild. But if the game is already decided, if you’re up or down six runs, you can shark without truly losing yourself in the moment. The Nationals understand this intuitively, and now you, too, can match your celebration to the occasion.