CHICAGO -- Second base has become a joint venture for the Cubs.

Since the team acquired Jeff Baker from the Rockies on July 2, they have faced only three left-handed starting pitchers, but Baker has been in the lineup at second each time, meaning he likely will start Wednesday against Houston's Mike Hampton. Mike Fontenot has continued to get most of the starts against right-handers.

The logic behind the platoon is simple. The right-handed Baker has mashed lefties in his career, with an OPS of nearly .900 against them, about 200 points better than his OPS against righties. The left-handed Fontenot's splits go in the other direction. Because of this, both players are accustomed to playing in a platoon situation.

"I've been in that role before," Baker said. "In Colorado, I played a lot against lefties. It's one of those situations where you know your role and get comfortable with it, and you go out there and roll with it and try to be productive the day you're in there."

Baker was hitting .130 with the Rockies. He also spent time on the disabled list before being dealt to the Cubs.

His first four starts with his new club came against righties, as the Cubs went through a long stretch without facing a lefty starter. Baker went 3-for-11 in those games and has since gone 3-for-9 with two doubles and two RBIs in three starts against southpaws. Baker also pinch-hit for Fontenot against Cincinnati left-handed reliever Daniel Ray Herrera on July 24 and smacked his first home run of the season to tie the game in the eighth inning. His batting average has climbed close to .200.

"It's progressing," Baker said of his swing. "I'm not where I need to be yet, but I'm getting to a spot where I'm getting better and putting myself in a position to make consistent contact."

Fontenot also has endured an up-and-down season, and he's currently mired in a 1-for-21 slide. Even though he said he believes he can hit left-handed pitchers, he understood manager Lou Piniella's tactic.

"I'm fine with it," Fontenot said. "There's nothing you can really do about it. I would never gripe and complain. I know my role, and I'll go out and play hard when I get the chance. ... When you go out there and play well, you're going to play, and if you're not, you know you're not. That's just the way it is, and that's the way it should be."

Even when Fontenot does not start, he often enters the game in the later innings as a defensive replacement or as a pinch-hitter against a right-handed reliever.

Piniella said he thought the platoon has "worked out OK" so far, although he wanted more offense from Fontenot.

"Baker's doing a very decent job," Piniella said. "He's been working hard with [bench coach Alan Trammell] on his defense. He's been making some nice plays out there. Fontenot defensively has played very well. We just need for him to swing the bat better than he has."

Pitching matchup
CHC: RHP Randy Wells (6-4, 3.10 ERA)
Wells seems to like facing National League Central teams. In his previous start, against the Reds, Wells picked up his ninth quality start and a victory. So far, he's 2-1 with a 2.39 ERA against NL Central teams and 6-0 when he gets at least four runs of support. Against the Reds, Wells' only mistake was serving up Aaron Harang's first career homer. Wells was kicking himself after the game for the slider he hung. He's still a rookie.

HOU: LHP Mike Hampton (6-7, 4.74 ERA)
In his previous start, against the New York Mets, Hampton couldn't make it through the sixth inning, allowing four runs on eight hits over 5 2/3 innings, but he did provide the Astros with a boost at the plate, hitting his first home run since May 8, 2005. It was the 16th of his career. Hampton has faced the Cubs once this season, taking the loss on May 6 after allowing five runs (three earned) on seven hits over 5 1/3 innings. In 24 career appearances, including 20 starts, he is 9-5 with a 3.07 ERA against the Cubs.

Tidbits
B.J. Ryan made his debut for Triple-A Iowa on Tuesday and pitched a scoreless inning against Omaha. Ryan gave up a one-out walk but then induced an inning-ending double play. The Cubs signed Ryan to Minor League deal after the Blue Jays released him July 8. ... The Cubs' 13-inning win over the Astros on Monday tied them with the Phillies for the second-most extra-inning games this season, with 13. The Blue Jays have 14. ... David Patton started for Double-A Tennessee on Monday and gave up two unearned runs on three hits in 2 2/3 innings. Patton is rehabbing a strained right groin that put him on the disabled list July 6. ... Infielder Bobby Scales, who spent time with the Cubs earlier this season, went 2-for-4 on Monday for Triple-A Iowa, giving him three multihit efforts in five games. ... Austin Bibens-Dirkx gave up one run, struck out seven and walked one in a complete-game victory for Class A Peoria on Monday. Bibens-Dirkx, a 16th-round pick of the Mariners in 2006, is in his first season in the Cubs' organization.

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Up next
• Thursday: Cubs (Kevin Hart, 2-1, 2.08) vs. Astros (Russ Ortiz, 3-5, 4.75), 1:20 p.m. CT
• Friday: Cubs (Rich Harden, 7-6, 4.55) at Marlins (Chris Volstad, 8-9, 4.44), 6:10 p.m. CT
• Saturday: Cubs (Carlos Zambrano, 7-4, 3.36) at Marlins (TBD), 6:10 p.m. CT