"We want to be the best middle infield we can be," Castro said, referring to his new partnership with shortstop Didi Gregorius. "We want to be the best middle infield in the major leagues."
Maybe they can be, maybe they can't. But the fact that Castro could even bring up the possibility in the first week of the 2016 season shows how smart and fortunate the Yankees have been the last two winters.
They needed a shortstop because Derek Jeter was retiring and they had no immediate successor in their system. They needed a second baseman because in the first two years after Robinson Cano left for Seattle, they used 10 players at the position without ever finding one they wanted to keep.
They knew they wanted to get younger and more athletic, but how do you do that if your farm system isn't ready to produce players at the positions you need?
Simple, if the Arizona Diamondbacks decide they're overloaded at shortstop and will move Gregorius at age 24. Simple, if the Chicago Cubs choose Addison Russell over Castro at shortstop and Ben Zobrist over Castro at second base when Castro's just 25.
Gregorius and Castro were young and athletic. They were talented. They also came to the Yankees with question marks, which is why the Yankees were able to get Castro for pitcher Adam Warren and infielder Brendan Ryan, and Gregorius in a three-team deal that cost them only pitcher Shane Greene.
Warren is a useful pitcher, but he didn't fit in the Yankee rotation and wasn't going to pitch at the back end of the bullpen, either. Greene has a good arm, but he wasn't going to find his way into the rotation.
The cost was more than reasonable—as long as Gregorius and Castro developed into a double-play combination the Yankees could win with.
It's too early to say they have, but the results look good so far. Gregorius started slow last year, but he emerged from Jeter's shadow to have a solid first season in New York. Castro started fast, becoming the first player in Yankee history to drive in seven runs in his first two games with the team.
"Starlin Castro is playing tee-ball right now," Yankees right fielder Carlos Beltran said.
Castro and Gregorius have looked comfortable together and comfortable as Yankees. Even if it's a little early to put them in the conversation as baseball's best double-play combination—it's hard to beat Carlos Correa and Jose Altuve of the Houston Astros—it may not be too early to say the Yankees have a middle-infield duo that can last.
They're certainly young enough. Gregorius turned 26 in February. Castro just got his 1,000th major league hit, but he only turned 26 last month.
Castro was a three-time All-Star before he turned 25, which speaks to his ability and potential. But he also had a reputation for swinging at everything and being slow to adapt.
Gregorius made top-prospect lists when he was coming up through the minor leagues with the Cincinnati Reds. But he was inconsistent enough in three seasons in Arizona that the Diamondbacks (and other teams) wondered if he would ever develop into a quality major league shortstop.
"They both came with questions," one American League executive said. "That's why they were available."
For now, it sure looks like the Yankees bought low on two undervalued talents. For now, it looks like the Yankees benefitted from the Diamondbacks' preference for playing Nick Ahmed at shortstop, and from the Cubs' need to move Castro after acquiring Russell and Zobrist.
The Cubs got Russell from the Oakland A's in July 2014 in the Jeff Samardzija-Jason Hammel trade, and almost immediately, there was talk that he'd replace Castro at shortstop. The switch finally came last August, at a point when Castro's performance had slipped both offensively and defensively.
"He knew there was a young player that was very talented behind him that might move him out of his spot," Yankees manager Joe Girardi told reporters recently. "I think that's difficult for players to accept."
As it turns out, the move may have helped Castro in the long run. When Cubs manager Joe Maddon put Russell at short, he started playing Castro at second base. The two months at second helped convince the Yankees he could play there full-time, and he ended up getting a new start with a team and fanbase that were ready to welcome him.
"It's a good opportunity to be in this organization," Castro said. "I just want to be the player I used to be."
It's early, but that's what Castro has looked like so far. It's early, but he and Gregorius look like a double-play combination the Yankees can win with.
Not bad for a couple of guys picked up on the cheap.
Danny Knobler covers Major League Baseball as a national columnist for Bleacher Report.
Follow Danny on Twitter and talk baseball.