In 2023, when José Caballero was with Seattle, he was already using the pitch clock to his advantage. MLB documented a game against the Yankees in which Caballero deliberately waited before making eye contact with Gerrit Cole until the required eight-second mark. Cole clearly noticed. Caballero afterward described it as manipulating the pitch clock. So this isn’t something Caballero suddenly started doing in pinstripes. Then fast-forward to 2026: Toronto got irritated by it.

On Saturday afternoon, during the Yankees’ matchup with the Atlanta Braves, the issue resurfaced in a much more consequential way. With one out in the bottom of the seventh, Caballero drew a walk but was called for a pitch-clock violation by home-plate umpire Dan Merzel for circumvention. Boone’s frustration centered on one detail: he believed Caballero should have been warned first.

Caballero was visibly upset by the call, slamming his equipment down before heading toward first base, where first-base coach Dan Fiorito had to guide him toward the bag. Then, before the inning could move on, Merzel called a pitch-clock violation on Austin Wells. Suddenly, Wells was beginning his at-bat with an 0-1 count, and Boone had seen enough.

The Yankees manager confronted Merzel and crew chief Dan Bellino after the inning, arguing that Caballero had not been given the warning he believed the rules required. The exchange became heated enough that Boone was caught on the broadcast while mic’d up. After the Yankees held on for a 5-4 victory, the manager had not cooled off.

“That was petty stuff going on,” Boone said. “I thought that was uncalled for.“You have to warn him,” Boone continued. “You have to warn him — unless I get a new memo from the league that changes [the rule] again.”

The controversy, however, isn’t simply that Caballero waits until the eight-second mark. MLB’s rules allow a batter to wait that long, provided he is in the box and alert to the pitcher by eight seconds. The issue is what Caballero does before that deadline. Umpires have determined that deliberately spending those final seconds looking down or otherwise withholding his attention from the pitcher can amount to “circumvention” if they believe he is trying to deceive the pitcher or manipulate the clock. That distinction became especially important after MLB began cracking down on Caballero’s routine in July.

Boone later made an important distinction: he was not necessarily insisting Caballero had done nothing wrong. He said he did not even see the sequence that produced the call and acknowledged there “might have been some circumvention.” His objection was that, in his view, there should have been a warning before the violation was enforced.

And that distinction matters because Caballero’s pitch-clock routine has already become one of the stranger recurring storylines surrounding the Yankees this season. He has made a habit of waiting until the final permitted moment to engage with pitchers, sometimes not raising his head until the eight-second mark, the latest point at which a batter must be alert to the pitcher.

The routine has irritated more than one opponent. In June, an umpire stopped play to address Caballero’s approach during a game against Toronto, while Boone said conversations about the issue with umpires seemed to be happening “once a series.” Then, in July, Pittsburgh reliever Dennis Santana’s frustration boiled over during a game with the Yankees, helping trigger a benches-clearing incident after Santana took exception to Caballero’s manipulation of the pitch timer. Caballero’s response afterward was almost perfectly in keeping with the way he views the tactic.

“If you get frustrated, I’m winning.”

That is the part that makes Saturday’s argument bigger than one disputed call. Caballero has spent months turning a tiny rule detail into a psychological battle. Opposing pitchers have complained about it, umpires have had to address it, and MLB has moved toward stricter enforcement of the rule’s language on circumvention. Now Boone, who once found Caballero’s antics irritating from the other side, is the manager arguing that the player is being treated unfairly.

Furthermore, Boone wasn’t always in Caballero’s corner. Before the Yankees acquired him from Tampa Bay, Boone admitted that Caballero had been the kind of opponent he hated facing. He was a “pest,” Boone said, and one he “didn’t like.” The calculation changed once Caballero became a Yankee.

That history makes Boone’s reaction Saturday particularly revealing. He wasn’t defending a player whose reputation he had never seen up close. He was defending a player whose ability to annoy opponents he had experienced himself, and whose increasingly complicated relationship with the pitch clock has now followed him from Seattle to Tampa Bay and finally to New York.

Aaron Boone once faced a test from Dan Merzel

There was another layer to Saturday’s argument, too: Merzel was not a new face for Boone.

In 2023, Boone was already among Major League Baseball’s more frequently ejected managers. After nine ejections in 2022, he received his fifth of the 2023 season during a July game against the St. Louis Cardinals, when he argued balls and strikes with Merzel during the third inning.

The argument did not immediately end when Boone was ejected. He continued exchanging words with Merzel before eventually making his way back toward the dugout.

Yet the Yankees manager’s assessment afterward was surprisingly warm.

“I think Dan is a really good, young umpire,” Boone said. “I really do.”

Three years later, Boone and Merzel found themselves in another argument, but the circumstances had changed. This time, Boone wasn’t disputing a strike zone call. He was objecting to how a rule was being enforced against a player whose peculiar pitch-clock routine had already caused problems across the league.

And instead of praising Merzel afterward, Boone left Yankee Stadium calling the situation “petty.”