The Phillies have placed SP Roy Oswalt on the disabled list with a back problem and have called up Scott Mathieson, 27, to take Oswalt’s place on the roster. In his nine appearances this year, Mathieson is 0-0 with a 4.61 ERA with one save in 13.2 innings of work. Mathieson has had some control issues walking 10 thus far, while striking out 15. Mathieson has stepped out of his normal late inning role with Lehigh Valley as of late throwing three plus innings a couple of times, logging over 50 pitches in those outings. Oswalt is eligible to come off the DL as soon as this coming Friday.