NEW YORK -- A day after offering tight-lipped silence in response to his tiff with Nationals outfielder Adam Eaton, the Mets’ Todd Frazier fired back, alluding to an incident between the two while they were White Sox teammates in 2016.

Frazier offered no details about the incident, chalking Eaton’s behavior up to “immaturity” and saying, “It’s in the past, but at the same time, you don’t forget about some things.”

“He understands where I’m coming from,” Frazier said. “He knows the past history. He’s going to have to take it, that’s it. I’ve said my piece. I’m done with it now unless something stirs it up. That’s about it.”

Asked about what happened in 2016, Eaton laughed and said, "What happened in 2016?"

"Man, he's like an old girlfriend," Eaton continued. "I'm not going to bring it up. Very childish, honestly."

During Monday’s 5-3 Mets win over the Nationals, Frazier and Eaton had to be separated as they barked at each other on the field between innings. While Frazier declined to discuss the incident afterward, Eaton said it stemmed from Frazier yelling at him throughout the game, and criticized his former teammate’s behavior.

“I’m a 30-year-old man with two kids, got a mortgage and everything,” Eaton said. “He wants to loud talk as he’s running off the field. At the end of the day, I got to be a man about it. I tried to stay patient with the childishness, but it is what it is. I got to stand up eventually.”

Asked about those comments Tuesday, Frazier broke his silence.

“That’s Adam. That’s him,” Frazier said. “At the end of the day, you think about what a man really is. … When I played with the White Sox in 2016, ask all 23 of those guys. They know what happened. For him to even talk after that, I don’t know how you talk after that. That’s basically all I’ll say about that. Men usually settle on the field. They don’t need to talk about it. But he started it, coming at me with that kind of, ‘I’m a man, I’ve got a mortgage to pay and two kids.' Pay off your mortgage. I don’t know what to tell you.”

Eaton, who has made more than $23 million in his career, clarified Tuesday that he does not actually have a mortgage.

Perhaps the two have buried the hatchet. Before Tuesday's game, they met on the field, talking at some length. Frazier and Eaton did not, however, hug or shake hands before departing.

As for the original spark of discontent, that remains a mystery. Frazier and Eaton spent just one season together in the White Sox organization, in 2016, lockering next to each other for a time before Chicago’s clubhouse staff separated them. Last year, Frazier verbally tangled with Eaton on the field, referencing a hard slide into second base that injured Mets infielder Phillip Evans. Frazier acknowledged Tuesday that Eaton’s slide was “part of” the issue, but he focused more of his anger on whatever happened in 2016.

“Nothing against the Nationals at all,” Frazier said. “This is between me and him. I’ve got the utmost respect for most of the guys over there. Hopefully it passes. Maybe it won’t. But that’s really it.”

From the trainer’s room

On April 16 in Philadelphia, Brandon Nimmo woke up with a stiff neck for the first time in his adult life. Two missed games, some muscle relaxers and a couple nights’ sleep seemed to do the trick; Nimmo was back in the lineup shortly thereafter.

But the neck issue never completely disappeared, sporadically bothering Nimmo as he hit .171/.312/.224 from that point forward. When Nimmo awoke Tuesday, he again felt soreness in his neck, resulting in the Mets scratching him from their lineup after batting practice. Nimmo planned to undergo an MRI on Wednesday to determine the root cause of his issues.

“It’s been off and on for four weeks now,” Nimmo said. “It would go away for a couple days and come back. … We’ll take a look, see if there’s anything that we can see.”

With Nimmo sidelined, Juan Lagares replaced him in center. By the eighth inning of Tuesday's 6-5 win over the Nationals, the Mets were left with an outfield consisting of two natural infielders -- Jeff McNeil and J.D. Davis -- and Carlos Gomez.

“I’m a little bit concerned about it,” Nimmo said. “Hopefully we’ll find out some answers tomorrow.”

Making progress

Michael Conforto began riding a stationary bike this week, marking his first physical activity since suffering a concussion last Thursday. The Mets plan to add more activities to Conforto’s regimen as tolerated, but they are offering no timetable for his return.