No one's going to get to do that. So whoever's throwing that day is the ace. Baldwin, admittedly new to the role, agreed. The guy who's the Opening Day starter isn't necessarily the ace of your staff down the line. It just depends on how it goes.
Aces differ in style and repertoire.
Some pile up strikeouts, hit three digits on the radar gun, play a power game, like Johnson and Martinez. Others, like Maddux and Glavine, rely on guile, changing speeds and pinpoint control. What it takes for a young pitcher to be a good pitcher is to figure himself out as a pitcher and don't try to be like other guys. If you don't trust what you're throwing, you're probably never going to win anything. Still star pitchers do share some common traits.