Murton, who's batting .276 overall, said he worked on both the mental and physical aspects of the game.
"It's a matter of me trusting myself and getting back to my stroke, and when I get those pitches, just let it fly and not try to do too much," he said.
He's nearly completed his first full first-half in the big leagues.
"I've learned a lot," Murton said. "There've been a lot of things I've faced in a short period of time. I'm starting to get a better feel. I'm not quite there yet. I'm gaining knowledge of pitch sequences. It's been a solid start; it hasn't been anything impressive. I find it to be somewhat average. I think there's a lot more in me, and it's just a matter of continuing to work."
The same can be said of Marmol, who earned his second Major League win. The rookie gave up one run on three hits and a season-high five walks over six innings, while striking out four.
"He was overthrowing early," Baker said. "He didn't start off too well. He settled down the more pitches he threw. That was big, him settling down after the first inning. Once he settled down, he was more in control.
"He's a kid who wants it and wants to stay here," Baker said. "That's what you like to see. You'd rather have a kid a little out of control that you have to rein in than someone you have to prod. We're all very proud of him."
Especially Cubs catcher Michael Barrett.
"It's not an easy lineup to pitch to, and he did a good job," Barrett said. "He kept them off balance and had real good stuff today."
"It's a good half for me," Marmol said. "I have to throw a lot more strikes and do what I have to do."
"He's a kid who wants it and wants to stay here. That's what you like to see. You'd rather have a kid a little out of control that you have to rein in than someone you have to prod. We're all very proud of him."
-- Dusty Baker, on Carlos Marmol
Marmol made the 32nd start by a Cubs rookie pitcher, and the kiddie corps now is 7-16 with a 5.83 ERA. It's the most starts by Cubs rookies since four youngsters, including Mark Prior and Carlos Zambrano, combined for 51 starts in 2002.
Barrett had four hits -- matching his career high, which he set July 2 against the White Sox -- and Ryan Dempster pitched the ninth for his 14th save in 19 opportunities.
Marmol escaped a first-inning jam he created by walking three batters to load the bases. The right-hander then struck out Bill Hall to end the inning.
"Larry [Rothschild] told me to calm down," Marmol said of a visit by the pitching coach after he'd walked the third batter. "Dusty did, too, and I tried to be nice and easy out there."
Damian Miller doubled to lead off the Brewers' second, and scored one out later on Dave Bush's double. That was it for Milwaukee.
Barrett singled to open the Cubs' fifth and scored on Murton's triple, only his third extra-base hit in his last 29 games. Ronny Cedeno then hit a sacrifice fly to put the Cubs ahead, 2-1. Murton added a run-scoring fielder's choice in the eighth off Matt Wise.
Marmol and Murton are two of the players Barrett looks forward to watching develop in the second half.
"The young talent that we have, guys are starting to look like they're getting settled in more," Barrett said. "Carlos and Sean Marshall look a lot more confident with each and every start. I think as we get this season going, their confidence will continue to build and they'll continue to give us quality starts.
"With young players, now is the time for them to turn things up," Barrett said. "You're fresh and you have a tendency to stay fresher. On top of that, Derrek Lee is probably the guy we'll look to the most to carry us in the second half. We have a lot of quality things to look forward to."