The Niese precedent, small sample that it is... Mets making Major League debuts as starters in pennant races: 9/3/73: Mets enter day in fifth place, 5.5 behind Cardinals; pull within 4.5 after they win and Cardinals lose respective twinbill openers; in nightcap, Craig Swan goes 4.1 IP, 4 ER, 9 H, 2 BB, 2 SO; Mets lose second game of doubleheader to Phillies at Shea; Swan pitches twice more in relief; Mets win pennant by 1.5 games; Swan wins 59 games as a Met between 1974 and 1984. 9/1/90: Mets enter day in second place, half-game behind Pirates; Julio Valera goes 6 IP, 3 ER, 5 H, 5 BB, 3 SO; Mets beat Giants at Shea; Valera starts one more game, gets rocked by Pirates; gets rocked in one additional relief appearance; Mets finish second by 4 games; Valera appears twice in relief in 1991; traded to California for Dick Schofield in 1992; wins 14 games between 1992 and 1996 for Angels and Royals. Mets making first Major League starts in pennant races: 9/26/07: Mets enter day in first place, 2 games ahead of Phillies; Phil Humber goes 4 IP, 5 ER, 6 H, 2 BB, 0 SO; Mets, having led 5-0, lose to Nationals at Shea; Humber made two relief appearances in September '06 and two more in September '07; hadn't pitched in 15 days prior to first start; last Met appearance; Mets finish second, 1 game behind Phillies; Humber traded to Twins for Johan Santana in 2008; called up to majors for first time in '08 in September.