I certainly don't think he lacks bat speed. He's just got an approach that's all flummoxed, and has failed at the internal game of figuring out what pitch to expect, what part of the plate to expect it, how to cover that part of the plate, and how to defend against being wrong. All players fail at it --- most fail seven times out of ten or more. But when you fail enough, you adjust your approach so much that you've lost faith in it and go up there clueless, and the slump becomes self-perpetuating. So you go back to basics. Start with one value and build off of that. Sometimes it's best to do that in the minors.