"I've got complete confidence in myself, and it's a long year," Dunn said. "I look back at last year, I had a great season, but I had probably 10-15 bad outings spread out over the course of six months. I've run into a rough patch right now."
Dunn is Miami's primary left-handed reliever, and as a veteran, he is expected to log late innings in close games.
Thus far, in 11 games and 8 2/3 innings, it's been rough for the left-hander. He's given up nine runs (eight earned), two homers and 12 hits. Dunn has struck out 11 and walked five.
In his last outing, at Atlanta on Wednesday, Dunn pitched one inning, and he was charged with two runs. Both scored on Evan Gattis' two-run double off A.J. Ramos, who inherited the runners, in the eighth inning.
"Last outing was tough," Dunn said. "I thought I threw the ball real well, and to give up two runs, that one was hard to swallow."
Physically, Dunn says he is fine. Twice this year, Miami manager Mike Redmond, accompanied by a trainer, checked on the left-hander.
"Physically, I'm 100 percent," he said. "I'm fine."
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter