One of the things the Phillies have been working with Velasquez is to get him to relax and not try to throw so hard.
When you can throw 105, if you don't try, you can throw 97-99 all day, and probably with much better command and movement, since you can focus on spin and mechanics instead of maxing out every pitch.
Look at Seranthony, boy doesn't even look like he's breathing heavy, throws 97-99, 98 MPH cutters (which simply isn't fair), and then drops an 86 MPH slider into the K-zone.
Hicks will either learn, blow out his arm or just be a flashy but inconsistent pitcher who wows you one inning, gets blown out the next when he walks himself into trouble.