I want him to be able to throw both. Not that he needs 100 pitches or anything, but beyond this level if he's not getting more then 2 pitches over in a game, he will struggle. Also, some of the scouts are telling me that that is what they want to see. I worked with him last night and really concentrated on him getting fastball arm extension and being a little tighter in the wrist and he actually threw some really good ones. He can feel the difference between throwing it right and throwing the slider so I think we are on the right track. Thanks guys. Im still going to try the tennis ball tube thing.