32 year-old reliever Mike Adams has a microscopic 1.70 ERA in 212 innings in his Padres career, spanning four seasons. He's under team control through next year, causing some to suggest the Padres' asking price will exceed that of closer Heath Bell.
Adams does have an injury history, including surgery to repair a torn labrum and damage to his rotator cuff in October of '08. He missed a little time with a shoulder strain in August of '09, after his return. Last year's injury was only an oblique strain, so on the bright side his arm and shoulder have been pretty healthy since the surgery.
The Rangers, Yankees, and Phillies are known to be in on Adams, and SI's Jon Heyman says Padres GM Jed Hoyer wants "a very big prospect" in return. Heyman explains that Rangers shortstop Jurickson Profar, generally considered among the ten or so best prospects in the game, would be too much.
On the other hand, Tom Krasovic reports that the Phillies are willing to trade first base/left field prospect Jonathan Singleton for Adams, but that might not be enough for San Diego. Singleton was ranked #24 on Keith Law's top 50 prospects list, but #41 on Baseball America's list. He failed to crack Kevin Goldstein's top 50 at Baseball Prospectus.
The prospect gurus are pretty far apart on Singleton, making it tough to identify the lower bound on the expected return for Adams. Still, if the two prospect-related Adams rumors are accurate, an appropriate return might be pitching prospects Robbie Erlin (Rangers) or Dellin Betances (Yankees).