He had an injury a couple of years ago. I think it was the hip. He played with it for quite some time, and serious compensations crept into his stroke. At the end, he couldn't keep his game together, and went through surgery. When he recovered from the surgery, he had issues with his stroke which I am not certain he has fully recovered from. Hopefully he will be back in good form soon.
2000: Hip surgery after winning twice that year.
2001: Won the Honda.
2002: Did not pass the $1-million mark for the first time since 1996.
2003: Fell further back
2004: Significantly better year with five top-10's in regular PGA Tour events.
2005: Quiet so far.
Have personally not seen him blaming the hip in interviews, but it might be the case.
Hope to see him back on the leaderboard.