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2/16/2014 4:24 P.M. ET

Dempster to sit out entire 2014 season

MESA, Ariz. -- When James Russell was a rookie reliever in Cubs camp, his locker was one of the wobbly extras in the middle of the room near the showers at Fitch Park. Ryan Dempster was at that time a starter for Chicago.

"I was terrified," Russell said about being in his first big league camp. "The first person who actually came up to say something to me was 'Demp.' He said, 'Hey man, there's an open locker next to me. Why don't you get out of that rollaway locker and come put your stuff in here?' I wasn't going to do it.

"The next day I come in, and all my stuff's right next to him," Russell said. "The stuff he does for young guys and the team is amazing."

On Sunday, Dempster said he would not pitch in 2014 because of health reasons. One of the most popular players in the game, the right-hander, who played for the Cubs from 2004-12, will be missed.

"He's one of the more standup guys in baseball," Russell said. "Him and [Alfonso] Soriano were two of the coolest personalities you could ever meet."

The Cubs players learned of Dempster's decision during their morning stretch.

"Me and Jeff [Samardzija] were really, really surprised," Russell said. "Just to even think of him not taking the ball [is tough]. He's one of the guys who no matter what, if he's hurting, he's out there grinding and trying to do what he can do to help the team."

If this is the end of his career, Dempster, who did not rule out a 2015 return, finished on a high note, winning the World Series with the Red Sox. Russell most recently communicated with Dempster in October, when he sent a congratulatory text.

In nine seasons with the Cubs, Dempster was 67-66 with a 3.74 ERA and 87 saves. He signed after undergoing Tommy John surgery and took over as closer from 2005-07 before returning to the rotation. In '06, he led the National League in games finished.

But it was Dempster's sense of humor and personality that endeared him. He would always invite players to his house, even if it was just to play video games. Dempster organized a Cubs "American Idol" competition one spring in which Russell took part.

After one season, Dempster took Russell and Andrew Cashner to the United Center in Chicago to watch the Blackhawks practice. Then they got a tour of the locker room and were allowed to suit up and skate.

"They let us go out and raise hell on the ice," Russell said. "I'm sure Ryan is the only one who could get that worked out."

Whether Dempster, 36, returns is up to him.

"You know he's doing it for the best interests of his career," Russell said of the decision. "I'd love to see him come back and play. He's still got plenty of years on his arm. It's sad to see that happen to a guy who is so well respected around baseball, and especially as well respected as he is in the city of Chicago and the guys in the locker room."

Castro top contender for Cubs' leadoff spot

MESA, Ariz. -- The Cubs have yet to play a game under new manager Rick Renteria, but it appears Starlin Castro is the top candidate to be the leadoff man.

Castro has a career .300 average batting first, but overall he also has a career .322 on-base percentage, which would not put in him the top 25 in the National League.

"Starlin has had that role in the past, and I think he did a pretty nice job," Renteria said Sunday. "He's not what you would consider a typical on-base guy. I think that as he continues to get more and more comfortable, hopefully, this year is a year he recovers some of his confidence and that little edge that he brought and that you guys all saw when he was coming up. He's an individual that is looking to do well."

Castro batted .300 in 2010, his rookie season, and followed that with a .307 average in '11. But last season, he struggled to bat .245.

Renteria is still tinkering with his lineup.

"We have the whole spring to develop a scheme as to who might fall into that role," he said.

After 'best year of life,' Bryant seeks another

MESA, Ariz. -- Exactly one year ago, the University of San Diego opened its college baseball season with a three-game series against San Diego State. Kris Bryant went 2-for-9 with a double that weekend.

On Sunday, he was in the Cubs' clubhouse, prepping for his first day of Spring Training.

"Last year, I was opening my college season, and that was a good season for me," he said. "It's crazy that a year has passed by, and it's been the best year of my life. It was a special one, and I'm ready to make 2014 a memorable one, too."

Bryant led the nation in home runs with San Diego in 2012-13, was the second pick overall in last June's First-Year Player Draft, then rocketed through the organization, beginning in Rookie ball and finishing in the Arizona Fall League.

He had boxes of gear waiting for him in his locker at the Cubs' new complex.

"When you sign and you're in professional baseball, I think that's what a lot of people like, is you get all the cool stuff and the latest gear," Bryant said. "That only helps you get better."

Bryant was eager to get started Sunday and hit with some of the other early-bird position players.

"It is a little different, but I've never been the type to like all the attention," he said. "There's a lot of guys in here who have been here a while, and the focus should be on them because they're the ones who have been here, and I haven't proven myself yet."

Bryant's parents and agents have tried to prep him for his first big league camp. Bryant does have some unfinished business with San Diego. He is one year shy of getting his finance degree, and he plans to return to school to complete it. But for now, it's all about the Cubs.

"No more school -- [I'm] studying baseball," Bryant said.

Cubs see change in former first-round pick

MESA, Ariz. -- It took a clinic with 9- and 10-year-old kids to help Brett Jackson find joy in baseball again.

Jackson is coming off a year he would like to forget. Once one of the Cubs' top prospects, the outfielder struggled with injuries and was demoted. He finished 2013 with a .210 average and 121 strikeouts in 95 Minor League games.

"It took a lot of hard work and a lot of soul searching," he said Sunday. "I've never been more excited to be back in Spring Training; I've never been more excited to be back on the field. When you're not playing well, the game's not fun. I wasn't having fun last year -- I was hurt and struggling.

"I rediscovered that fun a little bit this offseason," he said. "I feel I'm in the best physical shape I've been in and the best mental state I've been in in a long time. I'm very confident coming into camp and am excited to be part of this new regime."

Part of the change in attitude occurred because of the clinic that he and Lars Anderson conducted in Berkeley, Calif.

"I want to get back to that; I want to get back to playing for fun and playing for the guys and playing for the team," he said. "So much has been on performing on an individual level that I've forgotten the importance of why I play and the reason I play. I'm back to have fun and enjoy it and to win."

The Cubs have had high expectations for Jackson since selecting him in the first round of the 2009 First-Year Player Draft out of the University of California, Berkeley. He batted .297 in 2011 at Triple-A Iowa, but the next season hit .256 and struck out 158 times in 106 games.

Don't ask him about the strikeouts any more.

"It's something I'm not going to acknowledge moving forward," Jackson said. "I can't put a finger on it. The last couple years have been a search for finding myself at the plate and overcoming the pressures I was putting on myself. The strikeouts were in the corner of my mind -- being told I was striking out too much. Not to put the blame on anyone but myself. I'm confident in the adjustments I've made. That's something I can improve on."

The Cubs gave Jackson an offseason program that included improving his mental approach to the game. He addressed that as well as looking at videos of successful players. He hasn't reverted to his old swing, but it's more natural now.

"The changes I was trying to make last year had all the right intentions and all the right cues for me to become a better player," he said. "However, I was fighting my nature, I was fighting who I was as a natural athlete, and I think that made my time at the plate a struggle.

"Having said that, I'm thankful for last year, and I'm thankful for what happened and overcoming the injuries I had and the challenges I had at the plate and on the field. I feel the best I've felt moving into Spring Training."

Extra bases

Jake Arrieta, slowed this spring because of tightness in his right shoulder, is taking part in the Cubs' pitcher drills but has yet to throw off the mound. Arrieta has been able to play catch and is making progress, manager Rick Renteria said Sunday.

• Renteria, who had hip replacement surgery in October, walked around the Cubs' complex for nearly 45 minutes beginning at 5 a.m. MT on Sunday as part of his exercise. "The catchers are working early," Renteria said. "I'm not asking them to be out and do anything I wouldn't do. [My early work] kind of re-enforces that."

Albert Almora and Josh Vitters reported to Cubs camp on Sunday, joining Bryant and Brett Jackson. The first full-squad workout is Wednesday.

"I've been pretty impressed with the fact that the numbers are kind of high," Renteria said of the early birds. "It shows me a lot of interest. First of all, I'm sure they want to see the new facility. ... No one is making them be here, they've chosen to be here. It's nice to have them preparing for what will hopefully be a very good season."

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.