Should the National League Championship Series go the full seven games, the Mets will find themselves in the unenviable position of putting their entire season in the hands of Steve Trachsel, a pitcher who, in better circumstances might have been left out of the postseason rotation altogether, or entrusting the start to lefty middle reliever Darren Oliver, who did not start a game this year.

It says something about Trachsel that Oliver looks like the choice more likely to produce a happy outcome.

Despite his excellent performance in Game 3,throwing six innings of scoreless relief after the thigh-bruised Trachsel retreated to the trainer’s table, Oliver would be one of the unlikeliest choices in baseball history to start the seventh game of a postseason series. Though teams gave Oliver 228 starts in the years between 1993 and 2004,he was a notable failure. In the five years prior to coming to the Mets — not including 2005, a year Oliver spent out of the majors — Oliver made 100 starts. In 573 innings, he allowed nearly 700 hits. He walked 216, an average number, while striking out 319, or just five batters per nine innings pitched.His cumulative ERA of 5.83 was decidedly not average.

Oliver lacked the stuff to start. Unable to make batters swing and miss, he was forced to allow them to put the ball in play, and bad things happened when they did, including an abundance of home runs. Had Oliver been a righthander, his 2005 hiatus would likely have lasted the rest of his life, but being a southpaw means you never have to say die. The Mets took a chance on the journeyman and reaped a strong first half. Oliver’s 5.58 ERA after the All-Star break was redolent of his career numbers. Note that even in what was the best season of his career, Oliver allowed 13 home runs in 81 innings, a pace for roughly 30 in 200 innings.

Seventh games of postseason series are typically home to great pitching matchups, as teams try to go out (or hang on) with their best. In the 2003 ALCS, which featured the Yankees and the Red Sox, the seventh game was started by two future Hall of Famers, Pedro Martinez and Roger Clemens. Game Seven of the 2001 World Series was started by Clemens and Curt Schilling, the latter of whom, if he is not a future Hall of Famer, is nearly of that quality. Even the starters of the seventh game of the 2002 World Series, Livan Hernandez and John Lackey, had a greater claim to participation in a historic moment. Hernandez was a seven-year veteran with World Series experience while Lackey was a touted rookie.

There is little precedent for an Oliver start.One has to go back to a distant event like the 1948 American League playoff game between Boston and Cleveland, an infamous moment in Red Sox history in which manager Joe McCarthy, given an entire staff from which to pick his starter for the game of the year, including his ace, Mel Parnell, chose the sore-armed, seldom-used journeyman Denny Galehouse.Even that parallel isn’t perfect, for the Mets won’t be turning down any aces to start the deciding game. It will be an act of pure desperation.

Should the Mets carry this off, they will achieve something new in baseball, the patchwork pitching victory. The 1948 Braves had “Spahn and Sain and pray for rain,” but the Mets have “Glavine and pray for rain anyway so he can get a full four days rest.” Oldtime managers like McCarthy and Casey Stengel eschewed set rotations in favor of pitching the hot hand, often not deciding on a pitcher until the day of the game, but even then they were, with the exception of Denny Galehouse, choosing from a roster of established starters who generally had some track record of success. Don Larsen had started just 33 games over two seasons for the Yankees when Stengel tapped him to pitch what would become his perfect game in 1956, but those 33 starts were pretty good, resulting in a 20–7 record and a 3.18 ERA.

In Game 7 of the 1924 World Series, Washington Senators manager Bucky Harris started a decoy, right-hander Curly Ogden, in order to get Giants manager John McGraw to commit his left-handed platoon players. Then, after Ogden had faced two batters, Harris replaced him with lefty George Mogridge. When McGraw began to pinchhit for his good lefties, Harris switched back to a righty again.

Willie Randolph doesn’t have Don Larsen. He doesn’t even have George Mogridge. He has John Maine, a pitcher he and the organization didn’t even want in the postseason rotation; Oliver Perez, who was battered from April through October, and the shadow of Steve Trachsel’s courage.

When the Mets have won in the past, they’ve had strong pitchers to count on. Jerry Koosman started the final game of the 1969 World Series.Jon Matlack started Game 7 of the 1973 Series, though he lost. Ron Darling squared off against Bruce Hurst in the last game in 1986.Even in the ill-fated 2000 Series, the Mets were able to pit Al Leiter against Andy Pettitte in the deciding game.

The 2006 playoffs are a new kind of animal in Mets history. The chilling thing about it is, even if they pull it off, even if they somehow survive with the far-fetched improvisation that is Darren Oliver, even if Orlando Hernandez returns for the World Series, they’ll be hard-pressed to repeat the trick against the Detroit Tigers.

At some point, it really is necessary to have a starting rotation.

Mr. Goldman writes the Pinstriped Bible for www.yesnetwork.com and is the author of “Forging Genius,” a biography of Casey Stengel.