Rookie Mike Moustakas? Incumbent Wilson Betemit?
If you're looking for an answer from manager Ned Yost, as reporters did at the Winter Meetings on Tuesday, the answer would be Mike Aviles.
Nothing is definite or etched in stone. After all, it's not even Christmas yet, and who knows what Yost might find under his tree.
But there's no doubt that on Tuesday, Yost was leaning toward Aviles, the Royals' Player of the Year in 2008 as a hard-hitting shortstop.
"As we stand here today, yeah, I think Mike Aviles can play third base," Yost said. "I think he can do it efficiently and productively, but that's going to be up to him."
Aviles went through Tommy John surgery and lost most of 2009, then emerged as the primary second baseman last season when Chris Getz was injured and slumped. Aviles surged late in the season, suddenly finding his power (12 extra-base hits in his last 20 games) and throwing more like his pre-surgery days.
"He turned me around the last month of the season and really picked his game up offensively and defensively to the point where he's the type player that I like having on the field, but he's going to have to make it happen," Yost said.
Aviles finished the season with a .304 average, and six of his eight homers came in those last 20 games.
When Yost was asked if Minor League sensation Moustakas would get a shot at winning the third-base job, the manager hesitated.
"I wouldn't say that," Yost said. "I would say we plan to look at Moustakas. I'd feel better with that. I think we're going to come in and see where Moose is. Is he going to play a lot in Spring Training? Yeah. We're going to get a good look at him, see where he is and go from there."
General manager Dayton Moore has said all along that Moustakas was likely to start next season with Triple-A Omaha.
Betemit became the regular third baseman after Alberto Callaspo was traded to the Angels on July 22. Yost noted that Betemit did just fine in his first month on the job, but the manager noted his legs seemed to get "heavy" after that.
"He fits into a lot of places, because he's a very valuable guy -- a power-hitting switch-hitter that can hit for average," Yost said.
But Yost feels that Betemit would be more effective if limited to regular duty no more than four games a week and would be more valuable as a swing player at third, second or first base and in the outfield. As a switch-hitter, Betemit would give Yost a right-handed option in what currently is an all left-handed-hitting outfield -- Alex Gordon in left, Gregor Blanco or Jarrod Dyson in center and Mitch Maier in right.
Yost is also counting on Getz, coming off a season ended by a concussion, to resume his job as the regular second baseman. He sees Getz as important in helping the Royals shake off their shackles as the American League's lowest-ranking defensive team.
Yost will let the tussle between Billy Butler and Kila Ka'aihue over first base and designated hitter play out during spring camp. And he made it clear that he's extremely happy with the way shortstop Yuniesky Betancourt progressed both in the field and at the plate last year.
Pitching? Well, that all hinges on if ace Zack Greinke is traded or returns. And Yost sounded very much like a Greinke fan.
"I love Zack Greinke, I love his competitiveness," Yost said. "Watching the World Series and you watch [Tim] Lincecum throw, he reminds me of Zack a lot, because he's got pitches that he can put you away with right now."
Once Yost got rolling about Greinke, he could hardly stop.
"He's got a fastball that he can sink, that he cuts a little bit, that he gets up to 97 mph," said Yost. "He's got a put-away slider, a put-away changeup, he's a bona fide No. 1 starter. His competitiveness is unparalleled to anybody I've seen on the mound. He's a dogged competitor, wants to win with every fiber of his being. He's a phenomenal, talented player and we've got him for two more years, and that makes me happy.
"But Zack's like all of us, he wants to win, and Zack knows there's a short window to win. His career is not going to last forever and he wants to maximize the time he has. And we're trying to speed up the process for him -- we're trying to win, too. And when is that time going to come? Probably a year or two down the road, but he's of a mind that 'I want to win.' So if a situation develops and it makes sense for us, it's something we'll surely consider."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.