"Now I've got him doing that every day, and he's coming up and saying, 'I was a 10 today,' and I'm like, 'Nah,'" Sveum said. "I'm thinking, I was watching and there was that one little throw. I said, '10 is perfect.' [On Friday], he actually had a 10.
"He'll be honest. He'll say, 'Eight today.' I'll say, 'Eight -- c'mon. Two balls out of 20? That's not an eight.' When you give guys little goals like that, I think they have fun with it, too."
Castro led National League shortstops with 29 errors last season, his first full year in the big leagues. The goal, obviously, is to reduce the mistakes. He knows that. Castro, who turned 22 on March 24, has his eyes on a prize.
"Gold Glove -- that's what I want," Castro said. "That's what I'm working on. I'm going to try to get a Gold Glove this year for sure."
"The work ethic is better, the quality is better, the quantity is getting there," Sveum said. "You have to get the quality first as much as anything."
One of the goals is to get Castro to slow down a notch after he catches the ball so he can make more accurate throws.
"He's got a great arm," Sveum said. "You don't need to speed that arm up with feet being too fast. That gets a lot of young guys in trouble. He's been very, very receptive of everything I've asked him to do."
Castro started his defensive drills this offseason in his native Dominican Republic. The Cubs provided a house for him and his family to stay in near the team's academy in Boca Chica, and he worked on his throws, his footwork. He appreciates Sveum's input.
"He told me, 'Slow down, you need to know who's running, know if they hit a ground ball in the hole, know who's running, so you know how much time you have,'" Castro said. "Last year, that kind of ground ball, I'd throw the ball too hard and make an error."
They've discussed where Castro needs to position himself at second base to handle double plays in hopes of avoiding collisions.
One thing the Cubs don't have to talk to Castro about much is hitting. He was the youngest player to lead the National League in hits, totaling 207 last year. He's projected to bat third this year, although the numbers don't back it up. Last season, Castro batted .327 in 72 games as the leadoff man, .335 in 42 games in the No. 2 hole, and .225 in 42 games in the No. 3 spot. Sveum knows the numbers.
"It's a commitment I made," Sveum said. "He's still the best hitter on the team. Sometimes for the future of the team, too, you have to do it. When do you do it to a good young hitter? Does anybody know that answer? It's something I committed to, he's been committed to it and we talk about it, scoring position and all that.
"Rome wasn't built in a day, but just this last week, even though he doesn't have any hits, he's gotten better pitches to hit and he's looking more to the middle of the field," Sveum said. "Sometimes it's a learning process, too. For the future of the franchise, I think it's best to get him in there now."
Castro has hit third exclusively this spring and was batting .269 overall, .150 with runners in scoring position. In 2011, he hit .348 in Spring Training. He sticks to a regimen and does early hitting with Alfonso Soriano every day. The veteran is making sure Castro has good work habits. Castro said he's OK batting third.
"I feel good," he said. "I look at more pitches now, swing at strikes. I don't swing at bad pitches. I'm more aggressive with men in scoring position."
So, can the Cubs expect 200 hits again in 2012?
"I want to do that every year -- Gold Glove, 200 hits, All-Star Game again," he said. "I want to be a player who can put everything together -- hitting and defense. I want to do both, hitting and defense. When you miss an at-bat, don't go to the field and think about it, be ready for the pitch. Two worlds, different worlds -- it's the same game but different worlds. Your mind is on hitting when you hit."
To some, that may sound cocky. Castro shakes his head no when told that.
"I'll never be like that, no chance," he said. "Not even close."