Mets reliever Edwin Diaz pitches in the ninth inning against the Pirates...

Mets reliever Edwin Diaz pitches in the ninth inning against the Pirates at PNC Park on Saturday in Pittsburgh. Credit: Getty Images/Justin K. Aller

PITTSBURGH — The Mets have a closer question, and Mickey Callaway doesn’t appear to be communicating with Edwin Diaz about it.

After ardently sticking by Diaz (5.44 ERA) for four months, Callaway said Sunday that the Mets “have to be open-minded” about whom to use in the ninth inning of close games.

“I don’t think we can lock ourselves in to one thing,” Callaway said. “Moving forward, it’s just something that we’re going to do whatever we can to win a game that night. I don’t think we can lock ourselves in to one thing.”

That is a significant change from Callaway’s sentiment as recently as Wednesday, a day after Diaz’s fifth blown save, when he said: “Diaz is our closer. We’re going to do everything we can to get him in a better spot to continue to go out there and be our closer.”

Now Callaway says neither Diaz nor Seth Lugo (2.68 ERA) has a set role. Lugo, the National League Reliever of the Month in July, hasn’t allowed a run since June 29.

Has Callaway talked with Diaz about this pseudo-demotion?

“I think that at this point, he understands that he’s going to go out there when his name is called,” Callaway said.

Diaz said through a translator: “No, he hasn’t spoken to me about it. But whatever role there is, we’ll find out in the game today.”

The Mets didn’t find out Sunday, when they didn’t need any high-leverage relievers in a 13-2 win over the Pirates.

Diaz has allowed 10 home runs this season, tying his career high, and has given one up in three of his past four appearances. He said being removed as the closer wouldn’t affect his confidence and that he is “not surprised” about Callaway’s new open-roles philosophy.

“He can do what he needs to do,” Diaz said. “He’s the manager of the team. And the players are going to do what they have to do.

“Of course, I would love to be the closer. I feel like I’ve proven and my numbers in the past have said that I’m the closer of a team. If given the opportunity, I would want to do the same thing.”

Hart debuts

The Mets put Jacob Rhame, who was called up and pitched 1 1⁄3 scoreless innings Saturday, on the injured list with right elbow discomfort. To replace him, they promoted Donnie Hart, who was claimed off waivers from the Brewers on Saturday.

Hart, a sidearming lefthander, got three groundouts in a perfect eighth inning in which he needed only nine pitches.

“I liked the deception,” Callaway said. “There’s something there.”

Extra bases

Pete Alonso was out of the lineup Sunday for only the second time in more than two months. Callaway expects him to play in both games of Monday’s doubleheader against the Marlins. Jacob deGrom will start the opener and Walker Lockett will pitch the second game . . . Former Mets infielder T.J. Rivera signed with the Nationals and was assigned to their Double-A affiliate. He had been with the independent Long Island Ducks.

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