Roy Oswalt (back) is likely out until August. The veteran right-hander was diagnosed Saturday with a mild bulging disk in his lower back and admitted to reporters that he is worried about blowing it out. It's likely that the National League East-leading Phillies will tread cautiously with Oswalt, who has posted a 3.79 ERA and 1.33 WHIP in 71 1/3 innings this season. Kyle Kendrick and Vance Worley will continue to fill in.