First off, which O. Perez do you have. If it's oliver, then I think you already have a pretty strong team and may just want to wait and see what happens. I think you could trade pedro + a starting OF for a real ace or top tier RP and hope that one of your bench players steps it up. In fact, I think your more in need of a big time closer than another SP. I'm a life-long rangers fan, and thusly a real believer in Mench. He won't be spectacular, but kind of just plods along. I think .280/30/90 is a real possibility.