Consider this:
Basically, the Mariners have worked him hard all these years, and now when it's time to pay up or shut up, they're concerned about the effect all those innings have had on his pitching elbow.
From:
http://espn.go.com/mlb/story/_/id/89...al-source-says
Hernandez has been a workhorse in his career, throwing 1,620 1/3 innings already; in fact, since 1969, only three pitchers have thrown more innings before their 27th birthday, according to Elias Sports Bureau -- Bert Blyleven, Fernando Valenzuela and Dwight Gooden.