Who is the Greatest Pitcher of all time? Why?

I won't pick just one. It's too ridiculous to judge across eras, starting and relieving, good teams and bad. I don't think there IS just one. The problem for me is that once a guy gets the accolade, people don't want to change. So if it's Cy Young but later on a better pitcher comes along, the slower observers cling to Young as the answer. Off your list, the pitchers who were most dominant in their eras when compared to their peers would by Young, Sandy Koufax, Walter Johnson, and so on.