Castro doesn't turn 25 until March 20, yet he's already a three-time All-Star shortstop who draws the attention of the young Latin American players on the team.
''I'm not a real leader,'' Castro said Tuesday. ''I can help the young guys and I am still young, not a leader. We can be 25 guys leading the team and help each other.''
Cubs president of baseball operations Theo Epstein understands Castro's reluctance, but Epstein sees a player with more influence than he thinks.
''There is some humility to that, too,'' Epstein said. ''Normally the guys going around pounding their chest and saying they are the leaders of the team maybe aren't as much in reality.
''In his own way Starlin was really good last year especially when Javy Baez came up,'' Epstein said. ''He is someone (Castro) could see as a threat but he showed him the ropes and took him to dinner.''
With the addition of left-hander Jon Lester and catcher Miguel Montero and the rise of Anthony Rizzo in the clubhouse, much of the pressure could be off Castro, and that could help him concentrate on becoming more consistent on the field and making better decisions off it.
''You focus more because you got a guy behind you or in front of you that really wants to win,'' Castro said. ''You want to show those guys that you want to win, too.''
Boy, does he want to win. Castro was promoted to the Cubs from Double-A in 2010 as a 20-year-old and he hit .300. He had a down year in 2013 but bounced back nicely last year. However, the Cubs have finished fifth in each of his five seasons.
If Chicago is going to have its first winning season since 2009, it is vital for Castro to put up similar numbers to last year, when he hit .292 with 14 home runs and 65 RBIs in 134 games. He'll have the support of new manager Joe Maddon, who left Tampa Bay to join the Cubs.
''I don't really know him but everyone I ask no one tells me something bad,'' Castro said. ''They tell me something good. He took that team to playoffs and they aren't even close to what we got.
''I think it is going to be a really fun season,'' he said. ''We have a team we can compete against anyone.''
Castro came to Arizona a month early to work with strength and conditioning coach Tim Buss in an attempt to make sure he doesn't have the leg problems that has plagued him the last two springs.
Also, it allowed him to leave his home in the Dominican Republic where he was briefly detained - and had his home searched - by police after a nightclub shooting in December. Castro also acknowledged that earlier in the month he had left a nightclub before another shooting occurred.
Castro says he now understands the importance of who he spends his downtime with when away from the game, and he is considering buying home in the U.S.
''I can't put myself in situations. I can be in my house and not have a problem,'' he said. ''The problem isn't coming out of your house. The problems come when you are in the wrong place.''