Houston Astros ace Roy Oswalt will skip his next scheduled start because of lingering back problems. Oswalt was scheduled to start Tuesday night against San Francisco. But he threw 30 to 40 pitches in the bullpen Monday and was still feeling pain in his lower pain. Oswalt (6-4, 3.61 ERA) left in the second inning of Houston's 11-6 win in Chicago last week before of an irritated disk. The Astros hope slugger Lance Berkman and left-handed starter Wandy Rodriguez return this weekend...