His recent performances may not be doing much to change that fate.Halladay will try to prove he's worthy of returning next season, as he faces the Miami Marlins on Tuesday night for the first time since turning in one of the worst outings of his career.Halladay (3-4, 7.28 ERA), who unanimously won the 2010 NL Cy Young Award in his first season with Philadelphia, could be making his final start for the Phillies at Citizens Bank Park. Philadelphia (70-80) is off Thursday before hosting the New York Mets for a three-game series this weekend to conclude the home schedule.Halladay is 1-0 with a 5.06 ERA and 14 walks while hitting five batters in 21 1/3 innings over four starts since missing 3 1/2 months due to shoulder surgery.The 36-year-old right-hander didn't look anything like an eight-time All-Star against San Diego on Thursday, surrendering five runs in 4 1/3 innings of a 10-5 win, while issuing five walks for a second straight start."I realize I'm coming off surgery," Halladay said. "But I've worked extra hard to get back here and pitch -- and not only pitch but be successful. So it's personally frustrating when I'm not able to do what I want to do."That was certainly the case in a 14-2 loss to Miami on May 5, when he was tagged for nine runs with four walks before shoulder trouble forced him to exit with one out in the third. He ended up needing surgery, and didn't return until a 9-5 win over Arizona on Aug. 25.The Phillies, seemingly headed for their first losing season since 2002, defeated the Marlins 12-2 in Monday's opener for their sixth straight victory in the series. Cliff Lee allowed two runs in eight innings and helped himself with career highs of three hits and four RBIs.The Marlins (55-95), losers of nine of 11, are expected to give the ball to Brian Flynn (0-1, 10.13), who is bidding to become a member of next year's rotation.The 23-year-old left-handed rookie has fallen flat so far, failing to muster an out in the fifth inning while both of his starts ended in Marlins losses. He struggled again Thursday, surrendering six runs while issuing six walks in four innings of a 6-1 loss to Atlanta."You've got to be able to come up here and pound the strike zone," manager Mike Redmond told the team's official website. "Usually what gets young pitchers is getting behind good hitters. The strike zone is a little tighter up here, the hitters are a lot better. If you try to nibble on the corners and are not sharp, you're going to fall behind guys. The key is to get ahead and throw strikes."He has issued nine base on balls in eight innings with Miami after going 3-1 with a 1.16 ERA with nine walks over 46 2/3 innings in his final seven starts for Triple-A New Orleans before being recalled Sept. 3.