Dempster's won't start any playoff games and could be left off the roster entirely.
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.
The fact that Brett Anderson missed most of the season with an injury isn't a surprise. He made just 24 starts over the past three seasons due to multiple injuries. The fact that he hasn't been needed to fill a more integral role upon his return, however, and could be left off the playoff roster despite being healthy is a big surprise.
With rookies Sonny Gray and Dan Straily locking down rotation spots, there was no room for the 25-year-old Anderson, who was the team's Opening Day starter. Instead, he's pitched out of the bullpen, allowing 10 earned runs and 19 hits in 14.2 innings.
With lefties Sean Doolittle and Jerry Blevins each having terrific seasons, there's no need for Anderson to take up a spot.
When Jose Valverde fell apart in last year's playoffs, it was lefty Phil Coke who came to the rescue and earned the team's only two saves for the remainder of the playoffs. Despite picking up the loss in the deciding game four loss to the Giants in the World Series, Coke finished the postseason with an 0.84 ERA, two walks and 13 strikeouts in 10.2 innings pitched.
A year later, the Tigers find themselves headed back to the playoffs but the 31-year-old Coke might not be in the bullpen this time around. And it's unfortunate because he had bounced back from a rough start to the season (5.83 ERA in first half), allowing just one earned run in 10 innings over 19 games before a disastrous outing on September 18 (0.2 IP, 3 ER, 3 H, 2 BB).
Coke hasn't pitched since because of a sore elbow, making him a very unlikely option, especially now with Drew Smyly entrenched in the primary lefty setup man role.
There's no shame in losing the closer's job early in the season to the extremely talented Kenley Jansen. But Brandon League, who was re-signed to a three-year, $22.5 million contract prior to the season, hasn't been entrusted with a high-leverage role since—he has two holds and one blown save in the 2nd half—and it's not likely to change in the playoffs.
In fact, League has fallen behind several pitchers not with the club early in the season, including Brian Wilson, Carlos Marmol and rookie Chris Withrow.
Since a productive seven-appearance run (3-0, 8.2 IP, 0 R 4 H, 2 BB, 4 K) in July and August, the 30-year-old has allowed 10 earned runs and 23 hits in 13 innings pitched. He's lucky to be in a mop-up role right now. Unfortunately for him, a mop-up reliever isn't needed on the playoff roster.
Jake Westbrook pitched out of the bullpen during the 2011 playoffs and didn't pitch at all last postseason, although he was recovered from a late-season oblique injury. It's not that he didn't deserve a start. He's been a very solid back-of-the-rotation starter since the team acquired him at the 2010 trade deadline. But with Chris Carpenter and Kyle Lohse part of the rotation, he was the fifth best option.
If there was going to be a playoffs series when Westbrook would be needed, though, it looked as though it would be 2013. With Chris Carpenter and Jaime Garcia out for the entire season, the 35-year-old Westbrook would fill the role of veteran workhorse behind ace Adam Wainwright.
It appeared even more likely with Westbrook's ERA sitting at an impressive 2.95 after a July 24 victory over the Phillies. But he allowed 28 earned runs over his next 26 innings before landing on the disabled list with a lower back strain. He returned earlier this month but only to find there was no room him in the rotation with the way that young pitchers Michael Wacha and Joe Kelly were pitching. There won't be room in the bullpen, either.