Cishek, who has handled the closer's role since the All-Star break, had a rough ninth inning on Tuesday, giving up three runs in one-third of an inning.
The sidearm-throwing Cishek entered with a 3-0 lead, but three of the four batters he faced reached. Technically, the blown save went to Mike Dunn, who allowed the game-tying, two-run double to Brian McCann.
Miami did pull the game out, 4-3, in 10 innings. Afterward, manager Ozzie Guillen praised how well Cishek has pitched all season.
"For some reason, it's not going my way," Cishek said. "I go out there with the same mentality. I feel great, physically and mentally right now. I'm not getting the job done right now. That's basically it."
Tuesday wasn't his only spotty appearance of late. In September, Cishek has three saves, but in 6 1/3 innings, he has given up eight runs (seven earned).
The tough month comes after he was 7-for-7 in save chances in August, with a 2.70 ERA. For the season, he has a 2.87 ERA, with 14 saves in 18 chances.
Cishek has established career highs in innings pitched (59 2/3) and games (64). In 2011, his first full big league season, he appeared in 45 games, throwing 54 2/3 innings.
"I feel like I'm pitching the way I have all year, attacking with my fastball and slider," he said. "I'm keeping the ball relatively down. It's just not working my way right now. It happens. I'm trying to do my best to finish the season strong and help the team win."