Every baseball team enters the postseason hoping to win on the strengths of its best players. But it isn’t always the regular starters or a relief ace that determines the outcome.

With so few teams having four starters they can count on to get them through seven innings, everyone has to deal with the possibility that six months worth of baseball might hinge on the performance of the middle relievers, demoted starters, and situational specialists stuck in the back end of the bullpen.

It’s no secret that a team with a ninth-inning lead is likely to win. Since the onset of tri-divisional play in 1994, 91% of ninth-inning leads have been converted into wins. With a two or three-run lead, the numbers drop to only 85%. But clearly, it’s difficult to lose a game you’re leading with one frame to go.

The area where team performances are dramatically different is in how their bullpens perform outside of the ninth inning. This is where patient offenses make their money, wearing out the other team’s ninth or 12th pitcher, and scoring the runs that can make the late specialists mere spectators.

This is a particular source of concern for the Yankees and their fans. The rotation is less than a sure thing, reliant upon starters who have been inconsistent or are recovering from injuries. Nobody really relishes handing a sixth-inning lead to the likes of Tanyon Sturtze. With Paul Quantrill looking burned out from overuse, the Yankees need to worry.

Happily, Joe Torre’s willingness in Octobers past to use Mariano Rivera before the ninth inning allows him to use his best relievers earlier in games. Does anyone want Tom Gordon cleaning up a mess in the sixth inning? It’s a wise choice, given the alternatives.

Elsewhere in the American League, the contenders have their own sources of concern. The Red Sox have Scott Williamson hurting, and while Mike Timlin and Alan Embree are experienced, neither is having a great season. With the four-man rotation being the standard for the postseason, Red Sox manager Terry Francona could bump Tim Wakefield into the pen for a rubber-armed knuckleballer with plenty of bullpen experience. But would entrusting Bronson Arroyo with postseason starts be the best choice?

The Angels and the Athletics each have to shore up who will do what before the ninth inning. The Angels have seen all three of their previously reliable middle relievers – Brendan Donnelly, Scot Shields, and Kevin Gregg – struggle down the stretch. They might end up relying on Ramon Ortiz or Aaron Sele, neither of whom is likely to start a postseason game.

The A’s pen has been a problem all season, one that wasn’t fixed by the stretch pick-up of Octavio Dotel. Although middlemen Justin Duchscherer and Chris Hammond have done yeomen’s work, the combination of Chad Bradford, Ricardo Rincon, and Arthur Rhodes has been enormously disappointing in the later innings.

Only Minnesota is winding up the season with a bullpen marked by depth, health, and performance. Long before they need to call on Joe Nathan, the Twins can turn to flexible middlemen like Juan Rincon and J.C. Romero, and possibly rookie Jesse Crain.

The National League features several more pens not known for their famous contributors. That doesn’t have to be a handicap. Take the difference between the Cubs and the Braves. Whereas the Braves don’t have the names the Cubs do, they have good reason to rely on Chris Reitsma and Antonio Alfonseca before giving the game to John Smoltz. With his electric stuff and great year-to-date performance (one strikeout an inning, 2.66 ERA) Juan Cruz could be the sleeper star of the postseason.

Meanwhile, the Cubs have to sort through the injuries and ineffectiveness of Kyle Farnsworth and Mike Remlinger, and turn to a rehabbing Ryan Dempster in their short-handed desperation. The Astros might be even more desperate. Beyond Dan Miceli, manager Phil Garner is sifting through a number of choices, trying to find somebody else he can rely upon in the middle innings.

Out west, the Dodgers and Giants will rely on numbers, although different kinds. The Giants have to hope they can outscore their pen. Although they have a pair of good lefty situational relievers in Jason Christianson and Scott Eyre, righties Jim Brower, Matt Herges, and Tyler Walker are all shaky.

The Dodgers simply hope that their bullpen cast of thousands can cover for a fraying rotation. No-names like Duaner Sanchez, Giovanni Carrara, and Yhency Brazoban have done a good job, though manager Jim Tracy will likely show a quick hook if things go south.

The team with the pen most approaching perfection is the Cardinals. Keeping with his past habits, Tony La Russa has played the percentages, swapping in veteran lefties Ray King and Steve Kline with retread right-handers Cal Eldred, Julian Tavarez, and Kiko Calero. With Kline and Calero healthy, the Cardinals have their pen working exactly the way La Russa likes it entering October.

As Yankee fans know, there are always openings for unlikely heroes in the playoffs. In recent years, pitchers like Mike Stanton or Jeff Nelson have developed reputations for stellar postseason performance.

Another aspect of postseason success outside of the most famous moments is that it fuels endless speculation of whatifs. What if Buck Showalter had invested more trust in a young Mariano Rivera in 1995? Perhaps most sadly, there are still Phillies fans wondering what might have been, if only Roger Mason had been pitching to Joe Carter in 1993 instead of Mitch Williams.

It’s easy to second guess when you’re talking about a handful of innings with the season on the line.

This article was provided by Baseball Prospectus. The Sun will run exclusive content from Baseball Prospectus throughout the 2004 season. For more state-of-the-art baseball content, visit www.baseballprospectus.com.