It depends on your league format. In the points league that I'm in, he won't have any value if he's a reliever (assuming he doesn't close). But if you have roster room in a H2H or Roto and a need for a decent ERA and WHIP, and a fair number of K's, he may have some limited value. But he's a big question mark because we have no real idea what kind of shape he'll be in once he returns.
"This guy leads the league in most offensive categories, including nose hair..."