Roenicke obviously would have gone a different route had he known Marcum was going to allow four runs and last just one inning in Sunday night's 12-6 season-ending loss to the Cardinals in Game 6 of the National League Championship Series.
But as this slugfest unfolded, Roenicke was left to believe rolling the dice with Marcum was a better option than sending Yovani Gallardo to the mound on short rest or asking Chris Narveson to make his first start in three weeks.
"I know it was the right decision," Roenicke said. "I'm not second-guessing anything there. It was the right decision. With the options that we had, these guys pitched well all year. I still thought that they had good starts in them."
After boasting of the depth in his starting rotation throughout much of the season, Roenicke entered this win-or-go-home Game 6 with his fingers crossed and the hope that things would be different for Marcum, who had posted an 8.18 ERA in his previous six starts.
It did not take Marcum long to erase the optimism held by those who believed he would halt his recent struggles and extend the Brewers' season at least one more day. The 30-year-old right-hander entered this start determined to put a greater emphasis on his offspeed pitches.
Over the course of an entire game, this might have been the right way to attack the Cards' lineup. But it didn't seem to be the way to go when third baseman David Freese highlighted the four-run first inning by drilling a first-pitch changeup over the left-field wall for a three-run home run.
That essentially put an end to the season for Marcum. According to STATS, he became just the 21st pitcher since divisional play began in 1969 to allow four runs or more while lasting one inning or less in a postseason start.
"Obviously, pitching one inning, you can't be too happy about that," Marcum said. "You've got to give those guys credit. We'll head into this offseason and pick it up and come into Spring Training ready to go again."
Like Freese might have also homered had Marcum thrown a first-pitch fastball, the Cardinals provided every indication that they might have done just as much first-inning damage had the Brewers opted to give Narveson what would have been his first start since Sept. 25. The left-hander had not thrown more than 31 pitches in any of the five relief outings he had made since then.
Once Marcum had made his unceremonious exit, St. Louis pounded Narveson for five runs during the second and third innings. That Milwaukee fans to wonder if things might have been different had Gallardo been asked to pitch on short rest for the first time in his career.
But had Gallardo managed to help the Brewers win Game 6, Marcum and Narveson would have once again stood as the options to start Game 7.
"Physically, I think I could have done it," Narveson said. "But Marcum was our guy. He was the guy who has been there all year. You ride your horses."
Marcum might have been The Guy for Milwaukee for a portion of this season. But by the end, it was quite apparent he was not the same guy who went 12-5 with a 3.11 ERA in his first 29 starts of the season. Opponents batted .218 against him and homered once every 38.5 at-bats during that stretch.
During the seven starts that followed to close his season, Marcum went 1-5 with a 9.00 ERA. Opponents hit .348 against him and homered once every 17.6 at-bats.
"My body felt great," Marcum said. "My arm felt great. It was just the location on pitches. That's all it comes down to. If you make pitches and keep the ball down in the zone, it's hard for them to hit it out of the ballpark."
As Marcum stood at his locker and attempted to describe what had gone wrong, he talked about the fact that he struggled to command his changeup like he had in the past. But he never once indicated that he felt any kind of fatigue after completing a career-high 200 2/3 innings this year.
"I thought he was going to throw real well today," Brewers catcher Jonathan Lucroy said. "We had all the confidence in the world in him. He just made some mistakes. Obviously he's a little off. That's all I can say. He just hasn't been as sharp as he usually was during the season.
"To his credit, he carried us through the early part of the season. He was our horse. I think it is tough to get on him now, because he threw a lot of innings for us and got a lot of wins for us. He's one of the main reasons we are here."
Mark Bowman is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.