Free passes have been a reoccurring problem for Marmol this season, and they remain the one obstacle that could keep the Cubs' closer of the present from being their closer of the future.
"Obviously, he's the heir apparent here, and he deserves every opportunity," manager Lou Piniella said. "But at the same time, you put people on late in the ballgame, you don't make them hit their way on, it's an invitation for disaster."
Marmol (2-3) has shown a knack for wriggling out of self-imposed jams this season, but this time, he couldn't. Pinch-hitter Drew Sutton ripped a double into the right-field corner that scored both runners and led the Reds to a 7-5 victory that snapped the Cubs' four-game winning streak.
"With Marmol, it's the walks," Piniella said. "This young man wants to be a closer, and that's OK, but he's got to have command. If you don't have command, you can't close."
Behind three RBIs from a resurgent Geovany Soto, the Cubs had rallied from a 5-0 deficit to tie the game in the seventh inning after Chicago's infield defense let down starter Randy Wells with a three-error second.
But Marmol, who became the Cubs' closer Aug. 18 and has converted nine consecutive save opportunities, could not get the job done in a non-save situation. He gave up his first runs since Aug. 26.
"It's not different," Marmol said. "You're trying to get three outs, no matter what the situation is."
Early in the game, it looked like the Cubs' infield would be the team's downfall.
With Corky Miller on first and no outs in the third inning, Chicago made three errors in the span of four plays, leading to two runs. The strangest moment occurred when Drew Stubbs hit a routine double-play ball to third. Aramis Ramirez fielded it and threw toward second, but the ball caromed off Miller's helmet and out of play, allowing Miller to score.
"I've never seen that one before," Piniella said. "I didn't even know where the ball went."
The Cubs committed no more errors in the fourth, but that didn't mean the defense was much help to Wells. With one on and two out, the Reds hit three consecutive singles, including two that shortstop Ryan Theriot could not quite make plays on and one that bounced off first baseman Derrek Lee's glove.
Wells walked the next two hitters to force in a run and put the Cubs behind, 5-0. He left after 3 2/3 innings, matching his shortest outing of the season, and gave up five runs.
"To be honest with you, it was just one of those days," Wells said. "A couple bad hops, a couple of freak incidents. I really don't know what to say. I thought I threw the ball well. I thought I made some big pitches when I had to. I thought I made pitches all day, actually. Things just didn't go my way today."
The Cubs had one hit through five frames against Reds starter Johnny Cueto but scored three runs in the sixth, highlighted by Soto's RBI double off the left-field wall.
Soto came up again in the seventh with the bases loaded and two outs and ripped another double, into the gap in left-center field. Two runs scored to tie the game, but Ramirez was thrown out at home.
It has been a tough year for Soto, but he now has multiple RBIs in four consecutive games after his first three RBI effort since June 26.
"I feel good," Soto said. "The hits have been coming in, and I'm happy for it. But still, like I said, I have a lot of work to do. We have a lot of work to do."
Arthur Rhodes (1-1) pitched a scoreless eighth for the win, and Francisco Cordero retired the Cubs on nine pitches in the ninth for his 34th save.
Meanwhile, Chicago's closer has one thing to figure out.
"Obviously, his competitive spirit is good," Piniella said of Marmol. "His stuff is good. It's just a question of getting the damn thing over the plate."
Andrew Simon is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.