That was one of the simple, but profound, lessons the 300-game winner has impressed upon rookie pitcher Sean Marshall, his teammate, occasional pupil and current housemate.

The 23-year-old Marshall may be short on experience but he's long, quite literally at 6-foot-7, with promise. Consistency has yet to come. But with less than 10 starts to his big-league career, he's shown the knack for bouncing back from bad games.

The left-hander has gone from a relatively unknown rookie stopgap to a mainstay in the Cubs' rotation in a little over a month, since making his debut on April 9 in a Sunday night game at Wrigley Field against the St. Louis Cardinals.

"It's always been my dream to pitch in the Major Leagues, and the stars lined up right, so I had a chance to prove myself," Marshall said. "So far, I've done pretty well and hopefully I can keep doing well."

Since Marshall's debut, it became public knowledge that Maddux has served as a mentor of sorts for the rookie, comparing notes and giving tips on the bench during Marshall's starts. And that's not all. A late addition to the team out of Spring Training, Marshall has been gratefully bunking in Maddux's place until he finds accommodations in the city.

"I'm working on getting a place right now," Marshall said during the Cubs-White Sox series last weekend.

Until then, he'll continue to sponge off Maddux, so to speak.

"I talk to Greg and I watch Greg," he said. "I've watched Greg for a lot of years and he's had great success, and I'm just trying pick up stuff from him that can help me."

Learning from one's mistakes is something Marshall is sure to remember, especially after his most recent start.

Marshall dropped to 3-2 after his second straight subpar road outing Monday night in Florida. He gave up seven hits and seven runs in 3 1/3 innings, walking four and hitting two. His ERA shot up an entire run, going from 4.26 to 5.29. Marshall also gave up nine runs in 3 2/3 innings at San Francisco on May 11.

"I've learned that you're going to have games like that. It's baseball," Marshall said. "If you minimize your bad games like that one in San Francisco, you minimize those, you're going to have a good season."

But in between those games, Marshall pitched another gem at Wrigley Field -- six innings of shutout ball in a win over the Washington Nationals on May 17. He gave up just one hit, walking four and striking out six.

Not bad for a guy who was pitching in Class A Daytona last year at this time, and just last month was considered likely to return to Triple-A Iowa once Kerry Wood returned from the disabled list. Wood has since returned, and four other would-be starters have either been sent to the Minors or to the bullpen. Marshall, however, remains standing.

"One of the biggest keys for him this year is, he had a bad outing in San Francisco and turns around and has a great outing five days later and throws six innings, one hit," Cubs closer Ryan Dempster said. "That's pretty impressive right there. You don't see that out of a lot of young guys, and it's good to see."

Even with his Miami washout, Marshall has held hitters to a .214 average, fourth best in the National League (minimum one inning per game played) and is tied for sixth best in baseball. His walks -- about 4 1/2 per nine innings -- are high, but as his command improves, that should drop. He's striking out almost seven batters per nine innings.

Several Cubs, including manager Dusty Baker, have expressed admiration for the way the rookie has been able to shake off bad pitches, bad innings and bad games with aplomb. By his demeanor, you would never guess Marshall has just one less start in the Majors (nine) than he has in Double-A (10) and Triple-A (zero) combined.

Marshall has excelled at Wrigley, and it's not due to Maddux's home cooking. Marshall has stuck to a gameday routine where he eats steak and salad for lunch and a pregame snack of bratwurst. At home, he is 2-0 in four starts, limiting opponents to a .133 average. He's 1-2 on the road, where teams are hitting a robust .289 against him.

Against the Nationals, Marshall had trouble commanding his low-90s fastball, so he went to his changeup, which is quickly becoming a go-to pitch, if not an out pitch like his curveball.

"The changeup been working really well for me so I've been throwing it more than I have been the last couple years," Marshall said. "You just pitch with whatever you're having success with. Up here, it's about winning games and keeping your team in the game, and I've just been trying to pitch to what my strengths are so we could win."

Marshall was almost strictly a fastball-curveball pitcher while at Virginia Commonwealth University. Those two pitches alone were good enough to get him selected by the Cubs in the sixth round of the 2003 draft (one round behind his twin brother Brian, VCU's closer, who was released by the Boston Red Sox before the 2006 season).

Marshall had to beat out Rich Hill and Angel Guzman to make the Cubs' rotation out of Spring Training, and he did by pitching 10 2/3 scoreless innings over his five appearances. Both pitchers have joined the club since, and both have struggled. Hill was recently sent down to Triple-A Iowa after going 0-4 with a 9.13 ERA in four starts. Guzman went 0-2 with a 7.00 ERA in four outings.

"I think with him, he's very unafraid to come in and learn," Dempster said. "You see so many young guys, they come up to the big leagues and they see all the hoopla that comes with being a big leaguer and they fall into the trap and think they know it all. With him, he routinely tries to learn. He sits next to Maddux during the games and he tries to get better each time out.

"I think he's proving that sometimes experience and age doesn't matter as long as you just go out there and do what you got to do."

Marshall went 14-13 with an impressive 2.64 ERA in just 44 starts in the Minors, missing time in 2004 with a ruptured tendon in his left middle finger. Ranked sixth among Cubs farmhands by Baseball America after 2005 but never brought up in September, he still wasn't intimidated by joining the big leaguers in Spring Training.

"The key was just going out there with confidence and knowing I can have success up here," he said. "I watched guys in Spring Training pitch and just kind of compared myself to them. I think my tools are about even with them."

This story was not subject to the approval of Major League Baseball or its clubs.