Heyward said he recognized the balk immediately.
"[Carrasco] went to set and then he tried to go back and get another sign . . . without stepping off," Heyward said.
Even Carrasco couldn't argue the call by plate umpire James Hoye that scored Diory Hernandez from third.
"Yeah, as soon as he said it, it made sense," Carrasco said. "It's kind of like surreal . . .
"Not too many things get to me, but to lose a game like that, that's hard to swallow. You've got to let somebody at least hit the ball or do something else with it other than just balk in the winning run, so this is going to be a tough night for me."
Carrasco said he was worried he didn't see catcher Ronny Paulino's sign for a cutter and didn't want to cross up Paulino with Hernandez on third. When Paulino flashed the sign again, Carrasco paused before restarting his motion.
"I saw it," Mets manager Terry Collins said when asked if there was any question about the balk call.
Hernandez doubled with two outs in the 10th and took third after first baseman Lucas Duda mishandled Jordan Schafer's grounder. Hernandez scored the winning run on the balk.
It was all made possible by Brooks Conrad's two-run homer off Francisco Rodriguez in the bottom of the ninth. That came after the Mets took a two-run lead after coming back from a 6-2 deficit.
K-Rod hadn't blown a save since his first appearance for the Mets, who were trying to sweep a three-game series and go above .500 for the first time since April 6.
Chipper Jones had three hits, including a three-run homer, and five RBI before leaving the game in the ninth with a strained adductor muscle in his right leg. Gonzalez said Jones' status is day to day.
In other games:
* At Washington, Danny Espinosa's three-run homer in the bottom of the 10th gave the Nationals their sixth straight win, 7-4, over St. Louis, which has lost six straight.
"This has been close to happening for quite some time," said Jayson Werth, who 3 weeks ago said changes had to be made for the Nats to win regularly. "We've taken that step to win those games. We've finally got on a roll, and hopefully it keeps going."
* At Chicago, Kosuke Fukudome had three hits and broke it open with a three-run homer, Alfonso Soriano and Carlos Pena also went deep, and the Cubs beat the Milwaukee Brewers, 12-7.
* At Houston, Garrett Jones hit a three-run homer in the first inning and Pittsburgh added two runs in the sixth in a 5-4 win over the Astros.