It started gradually, as the Mets became the most compelling story in baseball over the last couple of weeks.

And now Michael Kay has been hearing it on his daily show on ESPN Radio, where passionate sports fans bark their opinions all afternoon. A strange but undeniable fact: Mets and Yankees fans are actually being civil toward one another.

Rarely in the 62 years since the Mets were born has the rivalry been anything but vitriolic. For decades, boroughs and homes were divided over allegiances. The owners of the teams even disliked one another, and the organizations battled for the city’s fans and attention. (The Yankees usually won, as they did on the field.) But for now, much of that old venom has dissipated, and the rants and rancor that once characterized this great, if lopsided, intracity rivalry, have cooled significantly.

“It’s weird,” said Mr. Kay, who was raised in the Bronx as a devoted Yankee fan. He is also the longtime announcer for the Yankees’ YES network. “When I was growing up, and even in 2000, everyone hated the other team. Now Yankee fans call in and say they are happy for Mets fans. I don’t get it.”

Perhaps it is driven by younger fans who do not remember the old malice, or maybe it is the sheer captivating joy and drama that the Mets have produced, almost on a nightly basis, from Grimace and OMG to stunning grand slams and improbable comeback victories. They did lose to the Dodgers on Thursday and trail in that series by three games to one, but perhaps there is one more miracle in store.

The Yankees, meanwhile, plod their way through the playoffs like a road grader, methodically advancing with far less drama, at least until Thursday, when they lost in 10 innings to the Cleveland Guardians. But they still lead the series, two games to one.