Spencer Arrighetti posted six shutout innings Thursday afternoon to lead the Astros to a 4-0 win over the Mariners. Arrighetti showed some improvement in his previous three starts. After allowing an 8.44 ERA in his first five starts, thanks in part to four home runs in 21 1/3 innings. In his last four starts, however, he did not allow a long ball, bringing his ERA for the stretch to 3.63. His walk rate improved as well, but still needs work.