Can someone explain why Cole Hamels' slider is so sick?

I think it’s the change-up that’s so killer, but if it’s a slider it’s the way he takes something off of it but keeps his arm in the same slot as a fastball.

There is absolutely no explanation. The man is a pitching God, and I am very sure you will be hearing his name along with the words cy young in the same sentence very soon.

I just can’t wait for his first No No.