Luckily for Rosales, his partner -- as well as the teammates of Ka'aihue and third baseman Brandon Inge, the other participant in the event -- is a golfer in the Special Olympics. When Thomas wasn't trash-talking Inge as the Major Leaguer lined up for his putt on the playoff hole, he was giving Rosales tips.
"It kind of feels like I'm [manager] Bob Melvin and this guy is my Little Leaguer or something like that," Thomas deadpanned, drawing a laugh from Rosales. "It was pretty cool."
"It was great," Rosales said. "[The other Special Olympians] came out, too. ... Ingy and Kila did a great job, too. It's nice to be the ultimate winner with Thomas right here. It was a great experience."
Of course, the putting challenge was just a fun diversion from the real purpose that the putting participants and other current and former A's players had for coming out on Thursday morning -- giving back.
The Golf Classic is the largest fundraiser for the A's Community Fund, which helps support local charities. It began in 1982, just one year after the Fund itself was established, and has been held since, with proceeds from the event going directly to the Fund.
Meanwhile, for the second straight year, the funds raised from a raffle held in conjunction with the Celebrity Putting Contest are benefiting the Special Olympics Northern California.
"To be honest with you, it's just fun to get out here," said Inge, who participated despite recovering from a right groin strain that forced him to the disabled list. "The competition's secondary. We just try and make it fun for the kids. That's the most important thing. ... It's a good cause, and we have fun with it."
While most of the excitement was generated by the Putting Contest, the majority of the Golf Classic centered around rounds of traditional golf on the Round Hill course, with current and former A's like Tommy Milone, Travis Blackley, Bert Campaneris, John "Blue Moon" Odom and others playing in groups with non-A's.
The day was capped off by an awards banquet and a live and silent auction.
Blackley, a left-handed reliever, said he's always happy to support charity and that it's something that all players should be wont to do, considering how much support that fans and the community give them.
Blackley also said that he loves golf days and enjoys getting away from the daily grind of baseball, so he was thrilled to participate on Thursday -- even though fellow reliever Jim Miller had to give him a ride, since the recently arrived Blackley is still living in a hotel and is without a car.
As far as his game goes, the Australian Blackley isn't exactly Greg Norman.
"I'm not that good at it," Blackley said. "I'll get mid-80s, somewhere in there; that's where I am about. I think if you're a little bit athletic, you can kind of keep the ball fair and put it in the hole.
"I walk up to the pro shop at most places and they look at me funny, and then I get out there and I'm actually better than they thought. That being said, I'll probably put one out of play on the first tee."
By comparison, Odom is much more talented on the fairways. He loves the Golf Classic and has been a fixture at the event for years, playing with a group of policemen, since he's a volunteer police officer himself.
And though he hasn't toed the rubber for 36 years, Odom still has a competitive streak. His team was going for its third straight win in the Classic, and before his round started, Odom was as focused as ever.
"I don't worry about [the competition]," Odom said. "I worry about my team. As long as my team is doing good, I know that the other teams are going to finish second."
But like all the other A's representatives on the course, the importance of charity -- the reason so many were gathered at Round Hill on Thursday -- wasn't lost on Odom.
"I'm happy that a lot of guys feel the same way I do," Odom said. "Back in the day, people didn't have a chance to do what we're doing. It's a great feeling to come out here and do something to help others, to help charities. I just enjoy doing it."