Arrieta cites mechanics for 2nd-half success

The key moment on Sunday, Cubs pitcher Jake Arrieta said, was in the fifth inning. Rookie catcher Victor Caratini had given Arrieta a heads-up before it began, even though the right-hander was facing the D-backs’ 7-8-9 hitters. It didn’t help that Arrieta walked both Ketel Marte and Gregor Blanco to start the inning.