Rosales, who grew up manning the middle infield at shortstop, had no time to waste waiting for a turn to play on the diamond rough. He was there to learn -- not watch.
So the always-eager Rosales did just that.
"They put me out there, and I got to learn how to play left field," he said. "I felt like it was the perfect time for me, developmental wise, to go to Mexico and get my at-bats and learn how to play a different position."
Rosales' flexibility and consistent hustle -- no matter where he's placed on the field -- are just two of the many reasons why he quickly became a fan favorite in Cincinnati last year. They're also why Billy Beane and the A's decided to pull the trigger and trade the more seasoned Aaron Miles for him -- and outfielder Willy Taveras, who was promptly designated for assignment -- in a four-player trade with the Reds on Monday.
"Our scouts have seen a lot of him over the past few years," said Beane's assistant general manager, David Forst, "and every single one of them just loves the way he plays the game and really likes his versatility."
In essence, Rosales represents the last key ingredient to the club's offseason recipe for what is hoped to be a playoff-caliber team. The A's now have depth at every position thanks to Rosales' potential to easily stand in for the still-unproven Cliff Pennington at shortstop -- the position at which the Reds drafted Rosales in 2005.
"It will definitely boost my confidence a little, just knowing somebody wants me," Rosales said Tuesday morning while driving near his home in Chicago. "That's what makes leaving the Reds a little bit easier. Any way I can help the team, I'm happy to be a part of it. I'm looking forward to winning."
The utility role is not exactly the most glamorous in baseball, but those familiar with the A's know it's a necessary one given the team's track record over the last three seasons with injuries -- a combined 64 uses of the disabled list.
"That's the role I was playing in Cincinnati, but I definitely don't want to limit myself," Rosales said. "Whatever the team needs I'm going to do, and I'm going to strive to reach my maximum potential."
Sounds like the standard line coming from a young guy simply looking to impress his new team. But Rosales is genuinely excited about the possibilities that come with a different organization -- even if it took him awhile to process it all.
Reds GM "Walt Jocketty called and said they had to make a move, and that there was a better opportunity in Oakland than there was in Cincinnati right now," he said. "It's the first time I've ever been traded. The Reds drafted me and gave me my first opportunity to be a professional baseball player.
"I had a little heartbreak feeling, but that's what baseball is, and I got a call from Billy Beane and he sounded excited to have me as part of the Oakland A's organization, so I was excited as well."
Rosales is also eager to become acquainted with a new league but even more ready to introduce said league to an all-out style of play some have compared to that of former Oakland fan favorite Eric Byrnes.
In 87 games last year, Rosales played all four infield positions while batting .213 with four home runs and 19 RBIs. He collected 49 hits and 26 walks -- all on which his 6-foot-2 frame ran at full speed.
"I haven't changed since I was a little kid," he said. "It's what I've always done. I like doing it. It keeps the energy up for myself and the game, and it tends to rub off a little bit on my teammates. When I was little I ran hard after a home run, although I didn't start hitting them until I was about 12 or 14. But I always ran to my position and played the game like it's supposed to be played as a kid."
As a Cubs fan growing up in Chicago, Rosales watched Brant Brown, "and I remember he ran around the bases really fast."
"It was something different and I thought, 'That's cool,' " Rosales said. "But I've just always learned from my coaches to play hard, and that was the consistent thing I learned each year. So I kept doing it all the way through college and into the Minor Leagues all the way to the Majors."
A man of many appreciations, including the travel and culture lessons learned while playing and living in Mexico for three months, Rosales never takes the game for granted.
"I'm just a typical baseball player who loves the game and has a passion for the game and wants to win," he said.
At the same time, Rosales is also just a twenty-something looking forward to California weather and a couple of harmonizing sessions here and there with any other willing guitar-playing A's.
"I'm just average," he said of his musical abilities. "I've played since high school but never got too serious. I'll pick it up every once in a while and play a new song."
Chances are it's a tune courtesy of Dave Matthews Band, the group Rosales claims to be his all-time favorite. Oh, and the A's newcomer also sings, too.
"Well," he said with a laugh," only when no one's watching."
Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.