I had a beer that I used WLP004 on turn out bad too. It was supposed to be an easy-drinking, smithwick's style, ale for a friend's wedding. The recipe was simple: Some 2-row pale, a little bit of crystal, a tiny bit of roasted barley, and goldings for bittering. Everything seemed to progress like all my other beers. It was awful. I can't even begin to figure out what happened.
I'm going to inflict a bottle on the local home brew shop to see if they can offer any advice.