Santillan was placed on the 15-day injured list Friday due to a back injury.
Santillan has apparently been dealing with the issue over the last few days and will be sidelined for at least two weeks. The exact nature and severity of his injury aren't yet clear, and he doesn't have a timetable to return. Art Warren and Alexis Diaz should see more work in the ninth inning while Santillan and Lucas Sims (back) are sidelined.