Eh I wouldn't say he can command the slider particularly well. What makes him so effective is his velocity but if you remove ticks off that to garner more command, his stuff isn't as good. It might be slightly sharper, but it's not nearly as deadly as it is when he can just rear back and throw.
He has trouble consistently locating the slider (which is why he doesn't throw it much anymore). The Change has the potential to be the best in baseball considering that it's physically impossible to get the timing difference down. But again he doesn't command it well yet so it's not a plus pitch.
It would be interesting to see but I think it'd just be wasting time. Much like with Mariano, he's just meant to be a closer.
We'll just have to agree to disagree here then. It is nice to find a MLB thread where you can have civil discussions about such things, I wish I would have started posting here longer ago.