Padres third baseman Chase Headley aims to make his 2013 season debut this week after fracturing his thumb in March.  Headley, who turns 29 in May, has a lot of factors conspiring to make him a trade candidate this summer:

• He's very good at baseball.  Headley's baseball card numbers last year were fantastic: 31 home runs and 115 RBIs.  He finished fifth in the NL MVP vote and snagged a Gold Glove and Silver Slugger.  He was worth 7.2 wins above replacement, sixth among all position players last year.
• To date, the Padres have not signed him to a long-term contract extension.  There's good reason for this.  As a player who came into his power later in his team-controlled career, Headley wasn't necessarily worth extending until this past offseason.  Now, with only one season of more than 12 home runs on his resume, it's likely difficult to pin down a fair offer for both sides.  Still, star-caliber non-Boras guys with four-plus years of big league service who are not locked up are a rarity.  2014 will be Headley's contract year, so he may prefer to just play it out and get a piece of that free agent pie.
• Headley is more than a rental, since he's under control through 2014.  Teams strongly prefer that when giving up top prospects in trades.  The general logic is that the Padres can get more for Headley this summer than during the offseason (assuming he plays decently upon his return).  Plus, even though the Padres have not reached an extension agreement with Headley, that exclusive extension window is valuable to some teams.
• Though only 7.4% of their season is in the books, the Padres are not looking like contenders, with a 2-10 record.  This can change, of course, but the team would need to play .580 ball from here on out to reach 89 wins.

This raises the question: which contenders could use a middle of the order third baseman?  

• The Yankees have Kevin Youkilis under contract, though Headley would be a better option at the hot corner.  Youk can also play first base, but Mark Teixeira will be back manning that position by the time trading season rolls around.  Travis Hafner seems a nice fit as the semi-regular designated hitter.  With his recovery from hip surgery and the Biogenesis situation, the Yankees shouldn't count on Alex Rodriguez for anything, but if he is able to play this year it will further clog up the third base and DH spots.  So while Headley would be nice to have, it'd be complicated, unless the Yankees suffer new injuries.
• The Blue Jays are all-in this year, and if they gain some comfort with the idea of Brett Lawrie at second base, they could add Headley and keep Jose Bautista in right field.
• The Royals appear set at third base with Mike Moustakas, but they could upgrade to Headley and include Moustakas in the trade.  This is another team that has invested a lot in winning now.
• It's a similar situation for the Indians and Lonnie Chisenhall — it seems like he'd have to be part of the deal for them to make sense.  
• Jeff Keppinger has been pressed into second base duty for the White Sox following Gordon Beckham's injury.  But either player could shift to a utility role with a Headley acquisition, or Beckham could be part of the deal.
• The Athletics have Josh Donaldson at third base, but Headley would be an upgrade.  Same goes for the Angels and Alberto Callaspo.  
• The National League is light on good trade partners for Headley at present, but the Braves are an obvious match.  He'd be a huge addition for a team that is looking great in the early going.
• I won't completely rule out the Orioles, Cardinals, Pirates, Rockies, or Dodgers.  But whether due to third base incumbents or the reduced chances of an intra-division trade, these teams seem unlikely.