At the age of 20, Hanley Ramirez had just 1 homer in 239 ABs for A+ Sarasota in 2004. I'm NOT saying Castro is the next Hanley, but it's just something to think about.
More of a potential upside with Nady. With Dye you know he can't hit righties at all at this point. Nady potentially gives you someone off the bench who isn't as limited offensively. I suppose. But if we were looking to acquire a right-handed PH (which is all Nady is at this point) then we should have just brought someone up off the farm.