By Eric Gilmore OAKLAND, Calif. – After pitching a four-hit shutout against the Seattle Mariners in his last start, rookie left-hander Brett Oberholtzer came up with an impressive encore Saturday against the Athletics. Oberholtzer allowed just one run on seven hits over six innings. He struck out five and didn’t walk a batter. But as luck would have it, Oberholtzer matched up against an A’s rookie who pitched even better. Right-hander Dan Straily blanked the Astros for seven innings on two hits, and the A’s held on for a 2-1 victory at the O.co Coliseum. Oberholtzer made only one costly mistake, hanging a 1-1 changeup in the fourth inning to [...]