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10/22/09 1:26 AM ET

Vitters vigilant about development

Cubs' first-rounder striving to improve defense in AFL

Cubs prospect Josh Vitters was given the "Most Polished Hitter" moniker in the 2007 Draft class for a reason. He makes every swing of the bat look powerful yet effortless.

But there's something that doesn't come naturally to the highly touted third baseman out of California: his defense.

"I'm just trying to work on everything [in the field] -- agility and always being ready at every pitch," Vitters said of his focus while playing for the Arizona Fall League's Mesa Solar Sox. "I know my hitting will always be there, and these things [on defense] will help me be better."

In that case, the errors column has been the only one with a zero next to Vitters' name. The 20-year-old went 3-for-5 with a two-run double and a run scored Wednesday night as Mesa held on for a 5-4 victory over the Scottsdale Scorpions.

Vitters doubled on his second swing of the night and, after a second-inning strikeout, delivered a single in the fourth that chased reliever Cesar Valdez (Diamondbacks). The Midwest League All-Star added a base hit in the seventh to raise his average to .400 through five AFL games.

Although Vitters looked plenty comfortable in the batter's box against the Scorpions, it hasn't all been smooth sailing in his first Fall League experience.

The former first-round pick went 5-for-8 in his first two games, then 0-for-7 in his next two as he struggled with facing pitchers he'd never seen before.

"In A-ball, you get to know the opposing team and pitchers better," Vitters said. "[The AFL is] kind of like starting all over again."

If his past success is any indicator, however, Vitters is a quick study.

Despite being slowed by a hand injury, Vitters was a Futures Game selection before earning a promotion to the Class A Advanced Florida State League, where he hit .237 with two homers, five doubles, two triples and 15 RBIs in 50 games at Daytona.

Vitters opened the season with Class A Peoria and batted .316 with 15 homers and 46 RBIs in 70 games. Although he's facing pitchers in the AFL with Double-A and Triple-A experience, he doesn't think he's overmatched.

"I don't think the talent level is much different at all [from the regular season]," Vitters said. "I just need to get used to facing pitchers I've never faced before. ... The competition is definitely better, but I'm trying to keep my game plan."

Marlins prospect Bryan Petersen also doubled and drove in a run, while Welington Castillo (Cubs) went 3-for-4 for Mesa (3-5). Solar Sox starter Tommy Mendoza (Angels) allowed an earned run on three hits over four innings to pick up his first fall win.

Giants catcher Buster Posey had two hits, two RBIs and a run scored for the Scorpions (4-4).

Brittany Ghiroli is a contributor to MLB.com This story was not subject to the approval of Major League Baseball or its clubs.