MESA, Ariz. -- Cubs pitcher Scott Baker, whose throwing program was suspended after his first Cactus League outing, called the setback "a little speed bump."
Baker, coming back from Tommy John surgery, underwent an MRI on his right elbow Monday and will be examined this weekend by Cubs orthopedic specialist Stephen Gryzlo.
"Right now, I'm choosing to be optimistic and hope for the best," Baker said Tuesday. "Obviously, any setback of any sort is not something you like to hear, but I think we'll know more when Dr. Gryzlo gets down here and he can do a physical exam. MRIs are great and everything, but you treat the patient, you don't treat the MRI."
On Sunday, Baker threw 23 pitches in his first spring start but failed to finish the first inning. He felt some discomfort in his right elbow on Monday and underwent an MRI that day.
"It's more disappointing for him, for a guy who's worked that hard and did everything and really did nothing to warrant something like this, being shutdown," Cubs manager Dale Sveum said. "Hopefully, it's not that big a deal, and he can continue. It's just a wait and see thing now."
There's no timetable for Baker's return, and the extent of the injury is not known. The Cubs had hoped Baker would be able to return by mid-April.
"From talking to guys, it's fairly uncommon not to have any setbacks," Baker said. "Thus far I haven't had any up until now. Is there ever a good time for a setback? Absolutely not. It is pretty common, but at the same time, it's not fun."
The team is already short-handed as far as the starting pitching, with Matt Garza not expected to return until the first week of May. He's been sidelined with a strained left lat, discovered during a live batting practice session Feb. 17. Garza has not been on the mound since then.
The Cubs began this spring feeling they had plenty of depth. Travis Wood and Carlos Villanueva will open the year in the rotation, filling Baker and Garza's spots. Another option could be lefty Chris Rusin, who has had a solid spring and started Tuesday against the Rangers.
"Garza is doing really well, so that's something we have to look forward to there," Sveum said. "If there's no setbacks, he'll be right on track, right around the first week of May. With Rusin, he's putting himself in that mix for the depth reasons and for a guy who had a lot of valuable time in the big leagues last year. Maybe that's why he's pitching so well in Spring Training...because of that experience he got last year."
Rusin spent most of the year at Triple-A Iowa, and went 2-3 in seven starts with the Cubs last season.
Baker did his homework after undergoing Tommy John surgery, asking other pitchers who had the procedure about what to expect.
"I feel fortunate to this point to not have any setbacks, and hopefully this is something that's a little speed bump and you keep moving," he said.
Schierholtz learning the quirks of Wrigley Field
MESA, Ariz. -- Nate Schierholtz has played nine games at Wrigley Field in his career, which isn't really enough to know all the quirks about right field there.
"I've played a handful of games there, not a ton, but I guess we'll see when we get there," Schierholtz said. "I want to work with [outfield coach] Dave McKay a lot, and get some early work in there and just figure out the dimensions, the park and the fence and all, and the wind. [The wind] is probably the biggest thing."
Schierholtz, who signed a one-year, $2.25 million contract with the Cubs, said McKay has covered every element of the outfield this spring.
"It's always great to go over anything that can happen out there," Schierholtz said. "After a long offseason, you need to refresh yourself. He's been great so far and I'm looking forward to working with him."
Stewart to open season on disabled list
MESA, Ariz. -- An MRI showed a pocket of fluid in Ian Stewart's left quad, and the Cubs third baseman will open the season on the disabled list.
The Cubs will see how Stewart responds to treatment over the next several days and then expect to have a better timetable for his progress.
Stewart said he felt something in his leg during a Minor League game last Thursday, and wasn't sure if that aggravated his left quad. It was his first game action since he injured his leg Feb. 21 in an intrasquad game.
There's stil pain, Stewart said Tuesday, and he hasn't been on the field since. On Monday, he tried to work out.
"I just tried to run, and can't run, can't get through the running part," Stewart said. "That's really the last hurdle. I can hit, take grounders, I just can't run."
Is he upset, frustrated?
"I would say frustration, because I can pretty much do everything somewhat pain-free without being able to run," Stewart said. "I know what it's like to play through pain and that's what's hard about this is I can't get through the pain because it's just too much."
Luis Valbuena is expected to start Opening Day, and Cubs manager Dale Sveum said Brent Lillibridge will make the 25-man roster. Lillibridge is a versatile player who can handle infield and outfield positions.
"Under the circumstances, it's pretty much a no-brainer [that he made the team]," Sveum said of Lillibridge, a non-roster invitee. "He's just too valuable a commodity."
Valbuena took over the starting third-base duties last season after Stewart needed surgery on his left wrist, and batted .219 in 90 games. Lillibridge played for the White Sox, Red Sox and Indians last season, and combined to bat .195 in 102 games.
The Cubs also will continue to consider non-roster invitees Alberto Gonzalez and Edwin Maysonet, who are in camp, and Sveum said they are checking the waiver wire as well.
"Basically, we have a spot open now," Sveum said. "Whether we do something within or through the waiver wires and guys being released these last two weeks, we'll have to wait and see. Obviously, it brings other people in camp into the mix."
Cubs third basemen combined to bat .201 with 12 home runs and 55 RBIs last season, the lowest production in the National League. The good news for Stewart this spring was that his wrist was healthy, and the Cubs were hoping to get at least 20 home runs and 70 plus RBIs from him.
The Cubs could platoon at third with Valbuena and Lillibridge.
"Valbuena does give you a pretty decent at-bat against left-handed pitching," Sveum said of the infielder, who batted .196 against lefties last year. "In the National League, there's one thing you like doing is keeping your bench fresh, because pinch-hitting is a big part of the game, and can win you one or two games a week, or two weeks."
Parker aims for spot in crowded 'pen after rough '12
MESA, Ariz. -- Cubs reliever Blake Parker has thrown 5 1/3 scoreless innings over five outings, and given up two hits to the 17 batters he's faced while walking one and striking out six. It's encouraging for the right-hander, who was limited to seven games with the big league team last season because of elbow soreness.
"This is exactly what I wanted to do is show them I'm ready and show them I can throw strikes and compete again after coming off the injury," Parker said. "I felt ready to come in and fight for a position, and feel I've done that."
There aren't many spots open in the Cubs' bullpen. Carlos Marmol, Kyuji Fujikawa, Shawn Camp and James Russell are set, plus the Cubs like what they've seen of Rule 5 Draft pick Hector Rondon. Other non-roster invitees still in camp and in contention include Drew Carpenter, Jaye Chapman, Casey Coleman, Jensen Lewis, Zach Putnam, Hisanori Takahashi and Cory Wade.
"There aren't many [openings] at all," Parker said. "There are a bunch of guys who have already proven themselves at the big league level."
Parker does have two options left, while others do not.
"You don't really worry about that," he said. "You go out and work your game and throw your pitches and see if that works."
His goal is to make it tough on the Cubs front office.
"You go out there and make the decision harder on them by being prepared every day," Parker said.
• Third-base coach David Bell had to leave Monday's game because he was feeling ill. He was not at HohoKam Stadium on Tuesday. Triple-A Iowa manager Marty Pevey handled third-base coaching duties on Tuesday.
• After an off-day Wednesday, the Cubs will play their final split-squad games on Thursday. Half of the team will go to Tucson to face the Dodgers at Kino Stadium to raise money for the Christina-Taylor Green Memorial Foundation. Green was one of six people killed in a shooting Jan. 8, 2011, in Tucson at an event to benefit Gabrielle Giffords. Green was 9 years old at the time. She was the granddaughter of former Cubs executive Dallas Green.
• Jeff Samardzija, the Cubs' Opening Day starter, will start against the Mariners in Peoria Thursday night.
• Cubs outfielder David DeJesus and teammate Anthony Rizzo will join Wade Miley, Adam Eaton, Casey Kelly and David Hernandez as celebrity bartenders Wednesday night at American Junkie in Scottsdale to raise money for the David DeJesus Family Foundation. General admission is $50.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.