The injury occurred in the fifth inning in Friday night's 6-4 extra-inning win against the Cincinnati Reds. McNeil squared to bunt, and as he pulled his bat back, he was hit by a curveball thrown by Brandon Williamson.
He stayed in the game after being checked by a trainer and even completed a double play in the top half of the sixth inning, but he was pulled for a pinch-hitter in the bottom half of the inning due to swelling in his wrist.
An MRI Saturday morning confirmed the fracture.
"This is not how you want to end the season," McNeil said. .".. I want to be out there with the guys. The team's done so much. You just want to help contribute."
McNeil who hit .326 to win the National League batting title in 2022, got off to a dreadful start to this season, hitting just .217 through June as the Mets were a 40-41 team at the time.
But he turned things around in July, hitting .260 for the month, and that coincided with the rise of the Mets.
After muddling around .500, the Mets are now 77-64 and in a tie for the third wildcard spot in the National League. They are 37-23 since the beginning of July, and Mendoza said McNeil was a key contributor to that.
"Huge blow," Mendoza said of the loss of McNeil. "The way he was playing, I would say right before probably two, couple of weeks before the All-Star break and the way he's been playing in the past two months - all the way through this point - you know, he's been a huge reason why we got... to this position. But everybody deals with injuries and guys will continue to step up."
Mendoza lauded McNeil for coming out of the early season doldrums.
"Proud of him because he fought and he never put his head down, and he was a big reason why our turnaround," the manager said.
On the season, McNeil is batting .238 with 57 runs, 12 homers and 44 RBIs in 129 games.
In 55 games since July 1st, he hit .271 with eight home runs and 25 RBIs.
It is expected Jose Iglesias will fill in for McNeil at second base.
