All five of Ruf's starts this season have come against left-handed pitchers. He is batting .278/.381/.333 with five RBI and two runs in 18 at-bats.
He made the team due to a monster spring training and presumably solid summer camp, and he also survived the first round of roster cuts Thursday. As long as he keeps getting on base at a strong clip against southpaws, the playing time should still be there, and he should eventually start hitting for power.