SEATTLE – The baseball had been struck a few minutes prior by Victor Martinez and caught by Michael Saunders, and now here it was in the Mariners clubhouse, being handed to rookie left-hander Roenis Elias as a keepsake to remind him of the best performance of his young professional career. “Thank you,” said Elias, who defected from Cuba in 2010, then worked his way through the Mariners’ minor league system, then was inserted into Seattle’s starting rotation after spring training this season despite never pitching above the Double-A level.