Johnson hits lefties just as well as righties. Anyway, I'm skeptical of this "new spots" theory. It seems to me, that the primary purpose of alternating left handed/right handed batters is to prevent the opposing manager from getting favorable lefty / righty matchups without burning through a new pitcher per batter.
Manny is obsessed with this crap. I'm getting awfully tired of Manny. He's as superstitious, stubborn, favoritism driven, and pigheaded as FR was.