I'd definitely get another free agent starter, but I'd also give both Sampson and Nieve shots at the rotation before I used Wandy, Buchholz, or Albers. Neither of those three rookies looks like they have good command of their fastball, especially under pressure. They seem to just aim to the middle and throw, hoping it is a strike that doesn't get belted. Until they ever gain real command, and I mean the ability and confidence to hit a spot with their fastball under pressure, I don't expect them to be major league starters.
Sampson on the other hand usually hits the mitt. Catcher sets up inside, pitch is inside. Catcher sets up outside, pitch is outside. He's way more advanced in the art of pitching. I would still like to see how he reacts under pressure, but so far, he looks like a real pitcher.