Not to mention that if Padilla can throw it for a strike on a consistent basis, it's a great 1st pitch because hitters aren't going to be swinging at it in a first pitch count.
Throws hitters timing off completely, so hitters have to have it in the back of their mind. It's not the plane, its the velocity, especially when he has another curveball. It's an effective pitch.
Because it makes sense to you, which means it is a bad idea
I'm just joking, though. I think Bard is a better long term solution, and with the new bargaining agreement, it's extremely important to have as cost-effective SP as possible.