his game right now isn't well suited for the course. You have to be more strategic and creative when called upon by the weather or pin locations. Add to this that you are required to hit the ball above or below your feet consistently and it just hasn't been a good fit for him.
The other majors, I am not sure what to say other than there are a lot of great golfers playing on the tour right now. He is getting sucked back into the pack as a result.