Sign guys with high floors.
Silva has had one bad year. Every other year he has been solid. If you're looking for flukes in his performance, it's the bad one, not the others.
Say you sign him to 4 years. Say you get two good years, two not so good. My contention is that in those 2 years in which he pitches well, the Reds are very likely to be contending for the division title in September. You gotta take that shot.