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05/01/2013 9:02 PM ET

Rizzo sees average rise thanks to adjustments

CHICAGO -- Baseball is a game of adjustments, and first baseman Anthony Rizzo knows all about that.

Rizzo entered Wednesday's game vs. the Padres 8-for-17 with four doubles, two home runs, six RBIs and four walks in his last five games to raise his average from .173 to .224.

"Everybody's making adjustments if they're struggling," manager Dale Sveum said. "Nine times out of 10, it comes down to confidence and getting a good pitch to hit and taking your walks and mentally being in a better place.

"A lot of times we talk about mechanics, and guys usually don't come out of slumps because of mechanical stuff," Sveum said. "It's because, one, they're everyday players, and two, they're really good and at the end of the year. The media guide doesn't lie. We all know each and every one of these guys will go into funks, and because they're every day players, they'll come out of it."

Rizzo finished the month of April with eight home runs, the most by a Cubs left-handed hitter for the first month. He also drove in 20 runs in the first month, which is the second highest total by a left-handed batter since Hall of Famer Billy Williams drove in 25 in April 1970.

Garza will make at least two more rehab starts

CHICAGO -- Matt Garza threw 2 2/3 innings Wednesday in a rehab start for Double-A Tennessee and will make at least two more Minor League starts before the team decides whether he's ready to return.

Garza was the losing pitcher in Tennessee's 3-0 loss to Mississippi, giving up one earned run on a hit and two walks. He threw 42 pitches, 25 for strikes. The right-hander is rehabbing from a strained left lat suffered in February.

"Everything went good and he felt great after it," manager Dale Sveum said Wednesday about Garza's outing.

Braeden Schlehuber put Mississippi on the board first in the bottom of the second with a two-out RBI single off Garza that scored Christian Marrero.

Stewart not ready to come off 15-day disabled list

CHICAGO -- Ian Stewart does not appear to be ready to be activated from the disabled list, and president of baseball operations Theo Epstein said the third baseman could be recertified to remain in the Minor Leagues.

Major League players are limited to 20 days per rehab assignment. Stewart's time expires on Friday, but Epstein said that's a "soft deadline."

"He's had bumps and bruises along the way, getting hit by a pitch, and having some soreness," Epstein said of Stewart, who is rehabbing with Triple-A Iowa. "We'll just monitor it daily and see what he's doing. He didn't have a Spring Training, so we look at this [time] as Spring Training."

Stewart strained his left quad in an intrasquad game Feb. 21 and did not play in Spring Training.

"There's nothing real good going on with his swing right now," manager Dale Sveum said. "I think he's seeing a lot of pitches and he is taking some walks, but there's no hard contact going on."

In 12 games with Iowa, Stewart was 4-for-40 (.100) with one double and four RBIs. He's struck out 15 times and walked eight times.

"He doesn't have his timing," Epstein said. "He's not been performing that well and his timing isn't there yet. He needs to keep playing."

Stewart does have an option remaining, so he could be activated off the disabled list and then sent to the Minors.

Extra bases

• The Cubs and the Robert R. McCormick Foundation announced more than $1 million in grants to nonprofit organizations serving those in need in the Chicago area.

Through Cubs Care, more than $18 million has been donated to Chicago nonprofit organizations since 1991. Events such as the Chicago Cubs Bricks and Ivy Ball, Race to Wrigley 5K Run presented by Athletico and Catch in the Confines, along with activities such as the Cubs Convention, personal scoreboard messages, financial contributions from players and private contributions from fans have helped raise funds for these efforts.

The 2013 grantees include the Chicago Park District, which provides access for more than 10,000 low-income and special needs youth to play baseball each summer. A donation to Union League Boys & Girls Club will expand baseball throughout Chicago with instruction and teamwork through Senior and Junior Cubs RBI (Reviving Baseball in the Inner Cities).

A donation to the Lake View YMCA will enhance their after-school program by incorporating a fitness and nutrition component to promote healthy lifestyles in youth.

• James Russell has thrown 11 scoreless innings over 14 appearances and is the first Cubs reliever in 44 years to not give up a run in the first month of the season while throwing at least 11 innings. The last reliever to do so was Ted Abernathy, who threw 16 2/3 shutout relief innings in April 1969. Russell's career high scoreless-innings streak is 14 from June 24-July 29, 2011.

Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat Joey Nowak contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.