I dont really think wandy has lost to much of a step, i think he is facing more consistent top level competition these days. Im not talking about since he came to the ufc, his last six fights have been against top level competition. Crocop, henderson, liddell, jardine, jackson, and franklin. That is a pretty tough stretch. If they did strength of schedule in mma then he would be near the top. I think he will get on another streak once he takes a couple of easier fights at middleweight.
You bring up a great point. His recent fights have been very challenging, more so than anyone else of late I would say. Wandy will always be one of my favorites. His fearlessness and willingness to accept a challenge has garnered much respect. To me he is brutality personified.