I DVR'd the game and flipped through to see what he's got. For someone who just got called up, he's un-freakin'-believable. Great command, stays low in the zone, five-alarm fastball with a killer change-up, changes speeds well, works with his catcher ... wow, what a debut.
The challenge for any pitcher with this kind of talent called up is staying on top of the scouting reports and being able to make adjustments. Eventually someone's going to get a book on him that works. He's got to show he's a student and not fall into the trap of "I've made it and it's always going to be this easy."
By the way he pitches, I'm guessing we shouldn't worry too much. He looked like the 3rd best pitcher on the staff right now, with the ability to crank it up more. Frankly, I'd be tempted to make him the closer just because it'd mean he'd get to impact that many more games.