I think I read somewhere that overdrying bats does improve performance, but only for a short period. I think their reasoning was that it stiffens the blade, therefore you get more energy transfer to the ball, but you trade off a large portion of the potential longevity of the blade, which could be down to fractures which occur during aggressive drying of the blade, and also just due to the lack of moisture to hold everything together. Could be massively wrong, and completely fabricated this in my head, but that was the general view I got from the post.