I thought Helling could have been used, but he hasn't pitched in a while, so I don't know what's up with him. Shouse also could have been used, but it's a toss-up. They really were the only two other options. Bush only lasted 3 innings last start, and will be missing a start Thursday. Why not see if he can spell the pen? I don't know for sure that I would have used Bush, but I can certainly see why Yost did. Makes sense to me.