Playoff rosters are constructed a bit differently than regular season rosters because teams don't need five starting pitchers or, in most cases, more than five or six bullpen arms because of the two expected days off in each five or seven-game series.
For this reason, teams are in a position to take the best group of pitchers, regardless of salary or past success, while struggling hitters who may have been the odd man out with a four or five-man bench aren't as likely to be left off.
In the case of Pirates first baseman/outfielder Garrett Jones, who is currently in a 4-for-31 slump and has lost his starting job after the acquisitions of Justin Morneau and Marlon Byrd, his ability to hit the ball out of the park—he has 99 homers in five seasons with the Bucs—gives him a solid shot at a playoff roster spot despite his lack of production in September.
A pitcher like Ryan Dempster, on the other hand, might not be as fortunate. A rough second half (5.22 ERA) ensured he would be the odd man out in the Red Sox rotation once Clay Buchholz returned from the disabled list. But a recent move to the 'pen—he pitched a scoreless inning on Saturday and another scoreless inning on Wednesday—might not allow him enough time to prove that he should be part of the playoff relief corps.
Here are four more notable pitchers who were expected to play bigger parts on their team's success but could be on the outside looking in once the playoffs start.