The term "Ace" seems to be really more of a fan and Sports Writer (or talking head on Sports Center) creation than anything else. A term used to soothe the feelings of uncertainty and angst that many feel due to the unknowns of baseball. I would argue that there is no such thing as a true "Ace". Rather there are Tiers of pitchers, and even within those Tiers there is some considerable variance based on factors such as health, experience, stamina, etc.. The term "True Ace" is a lot like unicorns and Bigfoot. Everybody talks about them, but they are rarely seen.