I didn't finish this before I had to return it to the library, but it was pretty helpful.
The author was/is a trainer for professional bowlers, and boy, he does not let you forget it! He mentions about a zillion anecdotes. "You should use this sort of approach, even though Joe Schmo used a different kind for years and won twelve PBA championships, and Mike Roller used THIS sort of approach and sucked until I helped him and then he won nine PBA titles" etc etc etc ad nauseum. You can skim all that stuff, though, and there's a lot of good advice in there.