Are D-backs Already Running Out of Pitching Depth?

With Merrill Kelly now expected to miss Opening Day and right-handers Cristian Mena and Brandon Pfaadt also added to the injury report, the Diamondbacks' once solid pitching depth already seems to be wearing thin. What's the latest on each of the D-backs' injured pitchers? Who could step up in their place? And who will start Opening Day in place of Kelly? Meanwhile, Zac Gallen and Eduardo Rodriguez made their first s