I never felt like Haren wasn't putting forth a credible effort. The only criticism I'd have is when he denied he had any ailments, and Rizzo put him on the DL anyway and he pitched better coming off it, which lent credibility to the thought that he actually WAS hurt.
But most of our players suffer the same conceit - "I'm not hurt, everything is good, leave me alone" even if their arm is falling off.