Drabek is in about the exact same position as Hutchison. With how good his control was, if he had come in throwing strikes each game in ST then it should have definitely had an influence. McGowan if he was healthy and had all his stuff working (mid-90's fastball + awesome off speed pitches) would have worked his way into the rotation. Even Romero, yeah if he all of a sudden looks like the old Romero (which AA hinted at his stuff all of a sudden looking better than it had in two years) then OF COURSE all of a sudden you need to start thinking about him over Happ.
It is called "position battles". It is not smart to lock up your rotation without even checking out the players in ST. The whole point to position battles is that it is already close between the players, whether it be injuries or results, so whoever looks better in ST should get them job. By better that doesn't mean results, but velocity, command, off speed stuff of course. And if a pitcher is showing that it usually follows that they'd be having good results in the spring.