The second baseman and shortstop combined to go 12-for-23 with four runs scored, nine RBIs and just three strikeouts over the opening three games. Castro especially has made his mark, leading the team in hits (seven), RBIs (eight) and extra-base hits (four) after going 2-for-4 with a home run on Thursday.
In Castro's mind, though, this high level of production might not have been possible without Gregorius' help.
"We're just talking everything," Castro said. "We're not only talking defensively, we're talking offensively, too. It's different because he's left-handed and I'm hitting right-handed, but he's telling me when I'm hitting before, 'Hey, I've faced that guy before,' or not. If he's faced him, he'll tell me."
Strategy hasn't been the pair's only talking point. Gregorius was in a similar situation last year to the one that Castro is in now when he joined the Yankees, a job made harder due to the fact that he was replacing Derek Jeter at shortstop. Armed with the memory of how he adjusted, Gregorius offered Castro some valuable advice on how to succeed in New York.
"I just told him to just play the game," Gregorius said. "Everything you do, people are going to find out. So if you do good on the field, you don't have to worry about anything. Just play the game and you'll do fine."
Gregorius, who played against Castro when they were both in the National League, said he wasn't surprised by Castro's early success. Nor was manager Joe Girardi, who said Thursday that Castro's performance is exactly what he expected when the Yankees acquired him from the Cubs during the offseason.
"If you look at the numbers he put up at the end of the season last year in Chicago, he did well," Girardi said. "So I just thought this would be a good place for him. Coming in new with a young shortstop in Didi and some veteran players around him, I thought this would be a good place for him."
New York has so far served as a good place for Castro, but so has the eighth hole in the lineup. Castro has a career .344 average batting eighth in limited at-bats. Despite his experience batting in the top third of the lineup, Castro said he doesn't have a preference and will be happy to stay batting eighth if it helps the team.
"I don't really want any spot," he said. "Whatever they want me to be, I'll be there. Whatever is good for the team, I'll do it. If they want me eight, I'm happy with that."