SAN DIEGO -- The Cubs knew Brett Jackson was striking out a lot at Triple-A Iowa, totaling 158 Ks in 106 games. But they didn't expect the outfielder to open his big league career with eight strikeouts in 11 at-bats.

Jackson did not start Wednesday in the Cubs' series finale against the Padres. Cubs manager Dale Sveum wanted to give the 24-year-old a day to catch his breath.

"Surprised [at the strikeouts]? Yeah, at that rate," Sveum said Wednesday. "I'm not surprised he's had some strikeouts. We knew that was going to happen. We're learning a lot about him, and it's basically come down to swinging out of the strike zone. It's not like he's swinging through anything."

One thing Jackson doesn't lack is confidence. The Cubs' first-round Draft pick in 2009, Jackson has handled the at-bats well.

"It's nothing he hasn't gone through -- not at this level," Sveum said. "This was part of the reason why we called him up, too, to see first hand and get a good grip on what's going on."

What can Sveum do?

"You don't want him to go up every at-bat and change," Sveum said. "[Tuesday] night, he probably had four different hand positions and three different set-ups. Those are the things you have to try to stay away from and let these kids let their athleticism come out, too.

"He's a confident kid who knows there's something a little wrong or something he needs to change to move forward and understand this is big league pitching, and they're not going to give in," Sveum said. "He's willing to make adjustments to succeed here."

Jackson, Vitters set to make Wrigley debuts

SAN DIEGO -- Thursday will be the first home game at Wrigley Field for Brett Jackson and Josh Vitters. They'll probably have a few butterflies.

Jackson and Vitters, promoted to the big leagues on Sunday, have been to the Cubs' home park before. Jackson remembers going to a game as a fan when he turned 19 and was playing in a college summer league in Wisconsin. He had a few days off, and he went with some friends to watch a Cubs game.

"It won't be as big of a breathtaking event as it was for others when it was the first time you walk into that place," Jackson said. "Fenway's like that, too. I remember walking into there and it's like, 'Wow, this is cool.' I guarantee you it'll still be pretty incredible."

Does he expect his heart to be pumping?

"My heart's still going right now," he said.

Vitters went to Wrigley after he was selected in the 2007 Draft.

"I'm not at all nervous," Vitters said. "I'm just excited to get there. It's going to be a big moment. I've been waiting for it for a long time. It's going to be a pretty surreal experience to be back there and playing for the team."

Both Vitters and Jackson were fortunate to begin their big league careers in California, which made it easier for their families to go to the games at Dodger Stadium and Petco Park. Jackson said his parents will be in Chicago for his first games at Wrigley Field.

"It's no secret they'll have to fight the nerves and work through that pressure, and pressure that is easy to add on ourselves," said rookie teammate Adrian Cardenas about what Jackson and Vitters can expect. "They're professionals. You saw Vitters make that play at third base [on Monday]. There were questions about his defense and there he goes, first day at third base, proving he could do it, and save a run at that in a close game.

"They'll obviously enjoy it but they're professionals, they've been playing this game for a long time," Cardenas said. "I think they'll be able to separate their emotions. When they come, I'm sure they can ask themselves, 'Hey, have I prepared for this moment?' and obviously, the answer is 'yes' for both of them."

Does Cardenas remember his first game at Wrigley? You bet.

"I wasn't as nervous as I thought I'd be," he said of his first at-bat, which came as a pinch-hitter on May 7. "I was more nervous my first start at second base, and it took way too long to get a ground ball -- six innings and then it was Chipper Jones who hit it, and I was 20 feet from first and I thought I would throw it into the stands, but I didn't.

"After that, you realize it's the same game," he said. "It's a cliche, but you're able to calm down and say, 'Hey, I can play at this level.' Even if it's just that first ground ball, after you've thrown it to first base, that's it. You can answer honestly that I've done it before. I think that kind of settles the nerves."

Castro hoping to finish season strong

SAN DIEGO -- Starlin Castro finished his first two seasons in the big leagues with a .300 batting average. But the Cubs shortstop is struggling -- he is currently hitting a career-low .272.

"I want to finish strong," Castro said. "Every [season], I finish strong. Every time, I put it in my mind that the last month, if you don't finish strong, my family doesn't eat. I put that in my mind. I need my family to eat these two months, like they eat in the first four months. I put that in my mind all the time. I'll do it for sure."

Castro has had a dropoff since Rudy Jaramillo was dismissed as the Cubs hitting coach on June 12. In 60 games with Jaramillo, Castro hit .308, and in the 48 games since, he's hitting .226. But Castro made it clear that new Cubs hitting coach James Rowson is not to blame.

"That guy is good -- he's unbelievable," Castro said of Rowson, promoted from his post as the Cubs Minor League coordinator. "He talks to you. I like him. He's kind of like Rudy -- it's almost the same guy. It's not because of him."

What Cubs manager Dale Sveum sees is the need to simplify things.

"There's so many moving parts that are going on that don't need to go on," Sveum said of Castro's swing. "There's not a good base on a consistent basis. ... There's so much movement going on, it's going to be hard to be consistent. He has to narrow things down to be able to use his hand-eye coordination."

Sveum said Castro, who led the National League in hits last season, doesn't need to alter too much, but may become a winter project.

"It's not like a big change -- it's making him understand he doesn't need all this extra movement going on to succeed," Sveum said.

Raley hopes to improve in second outing

SAN DIEGO -- Brooks Raley made his big league debut Tuesday for the Cubs, but was mad at himself the day after. The left-hander gave up seven runs over four innings against the Padres, striking out four, including leadoff man Chris Denorfia.

"There were some bright spots and I had some rough spots, but that's part of it," he said. "Obviously, I had high expectations for myself. That was the shortest outing of the year for me. I pride myself on going deep and throwing strikes. I might have been trying to do too much."

Raley has been on the fast track despite not opening the spring in the Cubs' big league camp. He started the season at Double-A Tennessee and moved up to Triple-A Iowa in late May. Now, he will likely stay in the rotation for the final two months. The Cubs are short-handed following the trades of Ryan Dempster and Paul Maholm and an injury to Matt Garza. Raley's next start will be Sunday at Wrigley Field against the Reds.

Give pitching coach Chris Bosio credit for helping Raley, 24, feel relaxed at the start.

"Bosio took me in the bullpen and after the first 15 pitches, he told me to sit down and kind of collect my thoughts," Raley said. "My first 15 [pitches], I don't even know where they were going. I thought that was the best way to handle that situation. I was able to calm down, finish my bullpen and warm up strong. I was ready to go first pitch. Striking out the first guy was awesome. I know I can be successful."

And he's got the baseball to prove it.

Extras bases

The Office of the Commissioner of Baseball announced Wednesday that Cubs Minor League pitcher Andin Diaz was suspended for violating the Minor League Drug Prevention and Treatment Program.

Diaz, a left-hander, has been suspended for 50 games without pay after testing positive for metabolites of Stanozolol.

The suspension of Diaz, who was currently on the roster of the Dominican Summer League Cubs, was effective immediately.