But after suffering a loss that seemingly ended any legitimate hopes of advancing to the postseason, his teammates were providing nothing but support toward Diaz, who was picked off third base to end the game with the bases loaded and the always-dangerous Martin Prado at the plate.
"You can't blame Matty," Atlanta first baseman Adam LaRoche said. "He's trying to be aggressive and sneak out a run there any way we can."
Diaz knew there was a chance that Marlins reliever Brendan Donnelly could throw a cutter into the dirt, and when he did with his first pitch, the Braves outfielder moved toward the plate and stopped when he realized catcher Ronny Paulino had turned himself around and found the ball as it bounced behind him.
Paulino rebounded in time to make a throw and beat a diving Diaz back to the third-base bag.
"I pride myself on making decisions -- not always the right ones, but decisive," Diaz said. "Right there, I hesitated, and it cost us big.
"When he picked up the ball, I thought, 'Whoa, wait a minute, I'm out.' So I tried to get in the line of fire from him going to third, hoping he'd hit me in the back or have it ricochet off my helmet and into left field. Like I said, I was indecisive, and that happened so quick, too. It wasn't until he picked up the ball that I realized I was in deep trouble."
Diaz's mistake concluded a loss that puts the Braves four games behind the front-running Rockies in the National League Wild Card race with just four games to play. Still, amid these circumstances, manager Bobby Cox was quick to describe Diaz as his team's best baserunner.
"If he goes right away, I think he might make it," Cox said. "I think he read the catcher not finding the ball. The catcher turned the wrong way and the ball popped out a little further. He just got in between ... We're going to win that game, Prado is either going to walk or hit a bullet somewhere."
While Diaz was visibly distraught, it was obvious that his teammates had brightened his spirits with their reactions.
"I've gotten a lot of pats on the butt," Diaz said. "We are a close team. That's one of the reasons that we were able to put together the run that we did to get back into this thing. We know we're in need of some serious help, maybe not necessarily from the Rockies, but maybe from up above. Maybe a miracle or something like that.
"It's a sinking feeling knowing that you've cost these guys. But it's a great feeling having them all pat you on the butt and say 'You're all right.'"
Mark Bowman is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.