But the growth chart for both young players has been a slow and grinding process this season. Castro, a two-time All-Star, has failed to get the job done on both offense, batting a career-worst .246, and defense (15 errors) this season. Although Castro's raw defensive skills have improved (he has a 22-game errorless streak) as far as fielding goes, insiders point to indecision and poor positioning as a weakness for the 23-year-old shortstop.
Rizzo, who has done well when making contact, has had his own problems on defense. Positioning for cutoff throws and calling cover plays have been challenging for him.
Meanwhile, Rizzo's batting average fell off to a season-low .232 after Wednesday's 0-for-3 performance in a 5-0 loss to the Cincinnati Reds. Rizzo, who had a long session with manager Dale Sveum during batting practice, squared up two balls that were caught in the loss.
"I hit one ball as hard as I can up the middle," Rizzo said. "The shortstop was playing up the middle. That is what I want to do, hit the ball up the middle. That is a part of the game you just have to keep rolling with it."
"You have to be able to hit the fastball," Sveum said before the game. "I will continue to say that until the day I die. If you can't hit the fastball you are going to struggle in this league. The bottom line is laying off the (bad) breaking ball. To strike the ball the bottom line is hitting the fastball. If you can't hit the fastball you can't play in the big leagues."
The pressure of carrying the lineup for both Rizzo and Castro may be too much responsibility. The Cubs have especially struggled offensively since Alfonso Soriano was traded to the New York Yankees on July 25. The Cubs have averaged 2.7 runs per game since the trade and they are 4-13 since July 29. Wednesday's loss dropped them to a season-low 16 games under .500.
"A lot of guys are now getting opportunities to step up and take advantage of it," Rizzo said. "It is not only myself that wants to do it but other guys on the team that haven't been here all year. I think it is time that all of us step up as a team together."