According to Jon Heyman, a few teams have spoken with the Padres about a potential trade for a starting pitcher.
A few teams have talked to padres about James shields. O's are one. Red sox have talked to SD about SP; shields logical— Jon Heyman (@JonHeyman) March 25, 2016
James Shields signed with the Padres in 2015, and in his first year with the club, threw 202.1 innings, posted an ERA of 3.91, along with an FIP of 4.45. It was the least productive year of his major league career (by fWAR) but as someone who's thrown at least 200 innings for nine consecutive seasons, it makes sense that he'd still draw interest on the trade market.
He struck out 9.61 batters per nine innings, which was a career high. The biggest problem for Shields last season was his penchant for allowing home runs. He surrendered 1.47 per nine innings, which was his worst rate since 2010. Heyman notes that the Orioles are interested in Shields, but isn't certain who the Red Sox are going after. It makes sense that both clubs are still targeting starting pitching, as their respective rotations are less than stellar.
For Baltimore, they're set to send out Chris Tillman, Yovani Gallardo, Miguel Gonzalez, Ubaldo Jimenez, and Mike Wright (at least for the first couple weeks of the regular season). That starting five doesn't inspire much confidence, and while Shields is coming off a down season, there's little reason to doubt that he'd at the very least be more valuable than Wright or Gonzalez.
As for the Red Sox, various scouts are worried about the strength of their rotation. Behind David Price, Boston has Rick Porcello, Clay Buchholz, Joe Kelly, and either Roenis Elias or Steven Wright. Shields would undoubtedly represent an upgrade over the latter two starters, and despite Kelly's fantastic spring training, it's hard to count on someone who pitched to the tune of a 4.82 ERA along with a 4.18 FIP. Given that Heyman didn't specifically connect the Red Sox to Shields, it's fair to wonder if Tyson Ross could be their primary target.
Before any trade talk for Shields can get serious however, there's one question that needs to be answered; what's his plan for using his opt-out? He has the ability to walk away from his current contract after the 2016 season, and re-enter free agency as a 35-year old. It seems unlikely that Shields would risk $44 million in guaranteed money, but stranger things have happened.
If he does plan on using the opt-out, then the Padres can't ask for many prospects in return, as he'd be a one year rental; however if Shields is content with his current contract, then he'd be a three-year asset (with a team option for 2019), which would dramatically change the asking price. It's unclear how far along any talks for Shields are, but given that San Diego acquired Craig Kimbrel on opening day of 2015, it wouldn't be surprising at all to see A.J. Preller make another late move.