The young shortstop received a reality check last season, however, starting slowly and never getting his game to the level he had flashed at the start of his Major League career. That's why Castro he said that he was proudest of himself for earning a trip to this year's game, where he'll have a ring seat to Derek Jeter's final All-Star Game.
"After that bad year last year, this is the best," said Castro, who is backing up the Rockies' Troy Tulowitzki. "Now I have the confidence back. I'm going to keep going every year."
While Rizzo and Castro are both 24, it took Rizzo a little longer to be recognized as one of the game's best players. But he's not exactly a grizzled veteran, as this is only his second full Major League season.
Like Castro, he learned some lessons the hard way a year ago.
Rizzo created large expectations by hitting . 285 with 15 home runs in 87 games after the Cubs promoted him at midseason in 2012, but he saw his batting average drop to .233 last year. His OPS was only slightly lower than the year before, dropping from .805 to .742, but some wondered if team president Theo Epstein & Co. had rated Rizzo too highly when they traded pitcher Andrew Cashner to the Padres for him.
"A lot of people write you off so quick in this game, which is, it's not unfair, but it is what it is," Rizzo said. "Castro, I'm really happy for him. He's gotten a lot better at shortstop, too, which is a big key to make our team a lot better. We're happy to be here."
Castro is hitting .276, which ranks third among the National League's regular shortstops. He has 11 home runs and 52 RBIs, the latter tied for second among shortstops. Castro's defensive metrics have also improved, although he still projects to 19 errors, down only slightly from 22 last season.
Rizzo is hitting .275 and leads NL first basemen with 20 home runs. Both he and Castro appear to have benefited from manager Rick Renteria using them as the Cubs' No. 3-4 hitters.
Rizzo sees a randomness to his performance this year relative to a year ago.
"Just baseball," Rizzo said. "Balls fall. Some balls that fell early give you a little more of an opportunity to relax. You don't have to press for hits. That's my biggest key. If I can get relaxed, great. If I'm pressing to get hits, it's really not going to be a good outcome."
Rizzo did admit that he's learned how to carry himself through bad times, good times and all those in between.
"Staying with the process, being even keel every day," Rizzo said. "Be the same person whether you're on a hot streak or you're in a bad slump. You have to come into the clubhouse and be the same guy, lead by example."
Castro credits Renteria for helping set the tone for his success this season.
"We talk," Castro said. "We talk a lot. He has the confidence in us. They trust us. They're letting us play baseball, that's the kind of [situation] you want. You have your talent. You know who you can be. You know you can be good. That's all you need -- people who trust you and let you play."
Rizzo wasn't disappointed to be left out of the lineup for the Gillette Home Run Derby. He said he would just be "soaking it all in" during his first trip to the event.
Like Castro, Rizzo hopes that he can become one of the NL's regulars.
"It's definitely something I strive for every year," Rizzo said. "I'm just going to try to keep getting better with the team."
Having two 24-year-old All-Stars counts as a major step in the right direction for the Cubs.