Arizona Diamondbacks right-hander Zac Gallen was forced to exit his start early against the San Diego Padres on Saturday afternoon, despite putting forward three of the sharper innings of the season prior to his removal. Gallen had been cruising through his start until he was struck in the right shoulder by a 92 MPH comebacker off the bat of Padres catcher Freddy Fermin. After a lengthy conversation with trainers and manager Torey Lovullo, Gallen stayed in to finish the inning, but was removed for right-hander Brandon Pfaadt ahead of the fourth inning. The D-backs called it a right shoulder contusion, officially — a diagnosis that carries a decent level of optimism. A contusion is, in essence, a bruise. And according to AZCentral's Nick Piecoro, the D-backs are optimistic about Gallen's status. The right-hander may not need to miss any time, and the team is "more encouraged today" that Gallen will be able to make his next start without spending any time down.…