Do we keep Michael Johnson ?

He was a big disappointment last year, with only 3 or 4 sacks. Someone told me he was injured, for much of the year, but played anyway.He is scheduled to make about 8 million this year, I think ?Both Bowers and Clayborne are free agents, and we may let them walk, so we don't really have many pass rushers left, if we let Johnson go, unless we get one in this years draft.