As the Yankees took two of three games from the Red Sox at Fenway Park over the weekend, acquiring Xavier Nady and Damaso Marte from the Pirates along the way, there was much speculation as to what kind of game the team should capture on its next trading safari. Much of the discussion centered on Mariners left-hander Jarrod Washburn, a relative mediocrity with an inappropriately large contract whom Seattle would like to unload, perhaps freighted with Jose Vidro, who may be the worst full-time designated hitter of all time.

The Yankees were reportedly close to a Washburn deal during the weekend, so the first question that presented itself was not, “What the heck do you do with Jose Vidro if the Mariners force you to take him?” This may be because “instant release/have security bar the door” would have seemed cruel, and “turn him into a backup catcher to replace Jorge Posada, now out for the season,” seemed impossible. Rather the most pressing question was which of the two pitchers at the back of the rotation Washburn, or a similar acquisition, should displace, Darrell Rasner or Sidney Ponson. But before such a decision is made about Rasner, Ponson, or any pitcher, the question has to be framed appropriately. A team can’t stop at asking which pitcher will help it get to the playoffs, but it also needs to think about how that pitcher will do in the playoffs themselves, because at that point the rules change.

This is especially true of the Yankees. The Pittsburgh Pirates or Milwaukee Brewers might be satisfied with a first-round playoff exit, but in recent years the Yankees have pretty much perfected the quick exit, and the novelty has worn off. Certainly it did for ownership and the front office, which is why Joe Torre is in Los Angeles and Joe Girardi is in New York.

The kind of baseball played in October is different from that played in most of the rest of the season. The weaker teams have gone home. The teams that are left behind represent a sampling of the best pitching staffs and offenses the game has to offer. As Sunday’s basting of dead-turkey Ponson by the Red Sox showed, the best hitters react very differently from the poor ones when confronted by a pitcher who doesn’t have strikeout stuff. The bad ones, say, the Royals, against whom Ponson pitched eight innings of six-hit, one-run ball on May 1, swing and miss at pitches that other batters would hit, and when they do make contact, the ball doesn’t go anywhere. Even if the hitters manage to put the ball in play, they don’t hit it for distance, or they have a Tony Pena Jr. (or Jose Vidro) or two gumming up the batting order, which means they can’t chain up sequences of hits into a big inning.

A potentially playoff-bound team like the Red Sox is very different. You serve up hittable pitches to a lineup that has Dustin Pedroia, Kevin Youkilis, David Ortiz, Manny Ramirez, Mike Lowell, and J.D. Drew in sequence, and they’re going to put the ball in play, likely in highly damaging ways. At that point, you’re in trouble no matter how good your offense is, because on most nights their pitching will be good enough to forestall a big rally — Daisuke Matsuzaka or Josh Beckett or Jon Lester will be stopping you from putting the ball in play.

In the regular season, the nondescript pitcher, the “innings eater,” is more valuable because, as Ponson showed in that start against the Royals, you don’t face playoff-bound teams every day. Instead, you have to worry about day-to-day matters that carry less weight in the playoffs, like keeping your bullpen from throwing too many innings. In the postseason, these types of starters are dead weight — but depending on the playoff schedule and a team’s rotation structure, they get to pitch anyway. There are always exceptions — hot pitchers, slumping bats, and lucky bounces — but in general, the more often innings eaters pitch, the sooner their team goes home.

If the Yankees do acquire another pitcher, get Chien-Ming Wang or Phil Hughes back from the disabled list, decide to bring back Ian Kennedy, or even if they simply stand pat, the question then becomes, who pitches after Joba Chamberlain, Andy Pettitte, and Mike Mussina, should they make the postseason?

Rasner’s problem in recent weeks has been one of command and endurance — he’s walked too many batters and hasn’t made it through the sixth inning since early June. He has, however, gotten the odd batter to swing and miss, averaging 5.9 strikeouts per nine innings for the season. This is just a bit below average for AL starters, who have struck out an average of 6.1 batters per nine. Ponson is averaging four strikeouts per nine innings. What he did against the Red Sox on Sunday was a preview of the postseason, and maybe that’s all you need to know.

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