The first rule for backup quarterbacking is also the only rule for backup quarterbacking and Mike McMahon figures that as long as he obeys, he someday will have a chance to obey it again. The rule begins with W and it ends there, too. He is the Eagles? No. 2 quarterback, and he has an opportunity now to keep it that way. Signed for another year, but with no guarantees, he is auditioning to be the reason Andy Reid can sleep at night next year without being haunted by the prospect of more games without Donovan McNabb. McMahon is 26 and he is trying to make sure he is employed, preferably by the Birds, at 27. "I don?t know about that," McMahon said. "I am just doing what I can now to help this team win games." So, he did Sunday, despite one of the more depressing boxscore lines a quarterback might yield. He didn?t throw for triple figures, setting for 97 passing yards. He was intercepted three times. He had no completion longer than 17 yards. He was sacked four times. He fumbled once, though the Eagles recovered. He had 17 rushing yards, but 15 of those were on one play.