CHICAGO -- As Edwin Díaz stood on the infield grass Sunday night at Wrigley Field, surrounded by a pair of umpires and two of his teammates, he quietly pleaded his case.

Crew chief Vic Carapazza turned Díaz’s palm upward and placed his own hand on it, trying to gauge the stickiness. Díaz’s hand was mottled with black, which he later explained was due to what he felt was a legal combination of dirt, rock rosin and sweat. He implored Carapazza to smell his hand to confirm that nothing illegal was on it.

Carapazza believed the stickiness was due to a different substance. He ejected Díaz, barring the closer from throwing a pitch in the Mets’ 5-2 win over the Cubs and lining him up for an automatic 10-game suspension.

“As soon as they saw me, they were trying to throw me out of the game,” Díaz said. “I understood. That’s their job. That’s part of the game.”

Díaz became the third Mets pitcher to receive a sticky stuff ejection in the last 15 months, joining Max Scherzer and Drew Smith. Entering a save situation in the bottom of the ninth inning, Díaz submitted to the same sticky stuff check that pitchers undergo on a regular basis, sometimes multiple times per game.

But this one quickly became anything but routine. Carapazza lingered by Díaz, checking his hat, belt and glove. Although Carapazza found nothing amiss in any of those places, he lingered on the pitcher’s right hand, checking it multiple times while home-plate umpire Alex Tosi watched.

“It definitely wasn’t rosin and sweat,” Carapazza later told a pool reporter. “We’ve checked thousands of these. I know what that feeling is. This was very sticky. … Without a question [it] was way too sticky. It didn’t take me very long.”

Neither Díaz nor Mets manager Carlos Mendoza put up much of an argument. Díaz did not ask for permission to wash his hands and return to the field, as Scherzer did last April. Following the game, Díaz said he only used legal substances to make his hands sticky. But MLB rules state that rosin, a legal substance, can become illegal if used in excess.

“We’ve got to do a better job, bottom line,” Mendoza said. “The rules are the rules. It’s a teaching moment.”

After Díaz departed, Smith entered but struggled to find his usual crispness, which he said was because he rushed to warm up. Ultimately, Jake Diekman recorded the final out in a victory that will have lasting effects for the team.

Assuming Díaz accepts his upcoming suspension without appeal, the Mets will be without their closer until July 6 as they play key series against the Yankees, Astros, Nationals and Pirates. They will not be able to replace Díaz on their roster during that time, which will force them to play shorthanded in the bullpen. The situation could even affect their plans to go to a six-man rotation in early July.

“It sucks,” said Smith, one of the pitchers suspended for a similar violation last June. “It sucks for everybody. It sucks for him. … It makes you feel bad. It hurts the team and personally, it’s not a fun feeling.”

Since MLB began instituting sticky substance checks in 2021, eight pitchers have been ejected for that reason. The Mets, with three, are the only team that has had multiple offenders. Asked why he believes that is, Smith offered a blanket “no comment,” reiterating that he didn’t use anything illegal before his suspension. Scherzer and Díaz made similar statements following their ejections.

“Obviously, the rules are the rules,” Mendoza said. “MLB is doing what they’re doing because they have really good reasons, and we’ve got to stand by it.”

The episode cast a pall over what would otherwise have been an uplifting victory for a Mets team that has won 13 of 17 to move back into the thick of the National League Wild Card race. It also further disjointed the recent career of Díaz, who missed all of last season recovering from patellar tendon surgery in his right knee. Díaz returned on Opening Day but blew four save opportunities in May, then spent time on the injured list due to a right shoulder impingement. He returned on June 13 and has since thrown three scoreless innings.

Whatever momentum Díaz gained over the past week will be frozen while he serves his suspension.

“It’s tough because I will let my teammates down for 10 games,” Díaz said. “That sucks, because I’ve been able to come back from the IL, I’ve been good and helped this team to win. Now to be out 10 more games, it sucks.”