The two runners left on base in the final frame mirrored a game that got away from the Marlins, who carried a three-run lead into the seventh inning before Atlanta rallied for its first win of the season.
The Marlins had plenty of opportunities, hammering out 12 hits and drawing five walks. But they also bounced into three double plays and went 4-for-16 with runners in scoring position while leaving 13 on base.
"We had plenty of chances to put them away early in the game," Realmuto said. "We just kind of let them hang around. You can't let that happen, when we have that many opportunities. That's something we need to get better at as a team. It's something we need to do more consistently to win ballgames."
The Marlins have now dropped two straight, and fell to 3-5. On Wednesday, after taking the first two games against the Mets, Miami fell, 2-1, in the series finale.
In the seventh inning of that game, the Marlins loaded the bases with no outs in a scoreless game but didn't score. That caught up to them, as the Mets came through in their half of the seventh.
In the series opener against Atlanta, there were more chances early. Even though they got some runs, the Marlins didn't get that game-breaking hit.
"We've got to bring it together when it matters. When there [are] two outs and a runner on second, we've got to get those hits," said Realmuto, who left seven runners on base. "We've got to get the outs when there are bases loaded and two outs.
"Instead of giving up flare hits, we've got to make pitches down in the zone and make those outs. Those are the most important outs in the game, and right now we're not executing them, on either side of the ball."
The way Wei-Yin Chen was throwing for the Marlins, it still appeared three runs would be enough. But the game turned in the late innings, and Atlanta scored four times in the eighth.
At that point, the Marlins' fears of early chances wasted became reality.
"When you're leaving a couple out there early, you do think about it," Marlins manager Don Mattingly said. "But the way Wei-Yin is going, you're thinking, OK, hopefully, you survive that. And it just kind of flipped on us."
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.