Simple. Until Rich Harden throws a spring training pitch, Sean Marshall is officially the 4th starter in my book, while Harden is relegated to the DL Watch. No, I'm not placing too much stress on spring training action. I'm just drawing the simple philosophical conclusion that if you're not pitching, you're not a pitcher. When Rich Harden returns to the mound without consolation or apology to the media from Lou Piniella, that's when I'll assume he's fine. But the biggest sign of a pitcher with no arm troubles is the actual throwing of pitches.
But based on what I've seen from Heilman and Marshall (you know, the guys who actually pitch for a living), I'm not too worried about the rotation.