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7/25/2014 2:03 A.M. ET

Jackson exits with cramping in right hand

CHICAGO -- Cubs pitcher Edwin Jackson had to leave Thursday's game after five-plus innings because of cramping in his right hand, a condition he's experienced in the past which has not forced him to miss a start.

The Cubs trailed 3-1 in the Padres' sixth when Yasmani Grandal walked and Will Venable singled against Jackson. Cubs athletic trainer PJ Mainville then went to the mound to check on the pitcher, and Jackson was then pulled.

Cubs manager Rick Renteria said they noticed Jackson shaking his right hand during the inning.

"He started shaking his hand a little bit," Renteria said. "The best thing to do was get him out of there."

Jackson threw 87 pitches, giving up seven hits, including Rene Rivera's home run in the fifth.

The Cubs will know more about Jackson's status on Friday. He said he's had cramping in his hand before, and did not miss his next start.

"It's one of those things where something can go wrong, it does," Jackson said.

Castro misses double-play partner Barney

CHICAGO -- Starlin Castro still uses a glove that Darwin Barney had made for the two of them. However, the Cubs shortstop has not talked to Barney since the second baseman was designated for assignment on Tuesday.

"I couldn't even believe it," Castro said Thursday about the transaction, which caught him off guard. "I come here two days ago, and I didn't see anything in his locker. It was really tough for me. We've been together in the middle since 2010."

Barney was the starting shortstop at Triple-A Iowa when Castro was promoted from Double-A to the big leagues in 2010, and started playing second base in the Minors. The two were paired together in the infield in mid-August that year.

"We were together all the time and had a good relationship, and now that happens, and I can't even believe it," Castro said. "Hopefully, another team will take him. Who knows?"

The Cubs decided to go with rookie Arismendy Alcantara over Barney, who was batting .230 in 72 games with the Cubs.

Castro has yet to talk to Barney since the move, and said he wanted to wait for a couple days. The two middle infielders had talked about someday both winning Gold Glove awards. Barney won his first in 2012. Castro plans to stay in touch.

"I'm going to call him when I need more gloves, and tell him to make me one," Castro said, smiling.

Ruggiano increases work with trainers

CHICAGO -- Cubs outfielder Justin Ruggiano was busy doing extra exercises with the athletic trainers early Thursday as he tries to deal with some tightness in his groin.

Ruggiano has not played since Tuesday. He was batting .378 with seven doubles, two homers and 14 RBIs in his last 21 games since June 25.

Cubs manager Rick Renteria said Ruggiano was feeling better Thursday.

"It's important that we make sure he maintains work with [the trainers]," Renteria said.

Black, Renteria reflect on Maddux's career

CHICAGO -- Padres manager Bud Black knows why Greg Maddux will be inducted into the Hall of Fame on Sunday.

"Early in his career, [Maddux] had velocity, he had movement, he had rotation," Black said Thursday. "So when you have those three things, it adds up to a Hall of Fame potential. When you combine that with the competitiveness, the head on the shoulders, the in-game awareness, the aptitude -- it adds up to a guy that separates himself for Hall of Fame status.

"As his career moved forward, he lost a little bit of the velocity," Black said, "but he still had the movement and location. You combine that with the experience and the pitching wisdom that he had moving forward -- again, it just adds to the Hall of Fame status."

Black said Maddux had "tremendous baseball instincts, the ability to locate the ball with tremendous movement through all of his career. That's what separated him."

Maddux will join baseball's elite in Cooperstown. The Hall of Fame induction ceremony will air on Sunday at 12:30 p.m. CT live on MLB Network and simulcast on MLB.com and the At-Bat app.

Cubs manager Rick Renteria was with the Padres with Black and Maddux in 2007-08, and also marveled at the right-hander's skills.

"The ability for him to stay healthy and do what he did is a gift," Renteria said of Maddux, who won 355 games in a 23-year career. "You're either born with the genes to do things like that or you're not. There are some things that contribute to the deterioration of the body at some point, but he was able to find something that kept him on the field a long time. He's a very gifted athlete, very good baseball player, very prepared and knew what he was doing."

Renteria said Maddux would correctly predict what would happen in the game from the dugout.

"He was very intuitive," Renteria said. "He'd be sitting in the dugout and say, 'This guy is going to hit this ball right between [the pitcher's] legs now,' and sure enough, we'd make the pitch, and boom, the guy would hit the ball between his legs. He had a knack of recognizing and knowing where the ball was going to be projected. When you saw him fielding when he pitched, he was many times already moving to the area where the ball was going to be batted to him."

Which could partly explain why Maddux won 18 Gold Gloves.

Extra bases

CHICAGO -- Cubs catcher Welington Castillo did not run hard to first when he grounded out to end the sixth inning Wednesday, and heard a few boos from the fans at Wrigley Field.

"I think that's a one-time thing for 'Welly,'" Cubs manager Rick Renteria said Thursday. "Not only were the fans upset about it but we were surprised by it. He knows. I think that's a very rare thing you saw from him."

• Reliever Justin Grimm had a tough inning Wednesday against the Padres, serving up three runs on two hits and three walks.

"His velocity is still good," Renteria said of Grimm. "We're trying to get what he does in the 'pen into the game. In talking to him [Wednesday], he knows he has to be able to command his pitches. We have to figure out what it is, if it's just emotion once he gets on the hill in a ballgame. Most of his preparation ... he really hits his spots prior to coming into the ballgame. We have to see if we can transition from there to the actual ballgame."

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.