To be fair to Crouch, it's not as if he misses many sitters. The quality of crosses coming in to the box has been woeful of late, and that's what he's going to score from. He was closer than anyone on sunday and that was a half chance.
Defoe missed two 1v1's against Villa and two against Liverpool, not to mention a penalty.
To be objective, there is nothing wrong with what lennon and bale do. The strikers must time their run in and position themselves intelligently to make space for opportunities to score. crouch just make the same run all the time making it very easy to close him out.