The team released the enigmatic left-hander Tuesday after Bedard slumped to his 14th loss of the season, tied for most in the majors, in a 7-0 drubbing by the Milwaukee Brewers on Sunday.
Pirates manager Clint Hurdle called the move "strictly performance related."
Bedard went 7-14 with a 5.01 ERA in 24 starts for Pittsburgh after signing a $4.5 million, one-year contract in December. The 33-year-old pitcher struggled over the last two months even as Pittsburgh rose to playoff contention. He was particularly ineffective on the road, going 3-9 with a 6.98 ERA in 12 starts away from PNC Park.
"We tried to find a rhythm and a rhyme to get him on a roll and weren't able to do it," Hurdle said. "A decision was made we'd be better served going in another direction."
The Pirates have not announced who will take Bedard's spot in the rotation, though Hurdle suggested they may go to a four-man rotation. Pittsburgh, which began the day three games behind St. Louis for an NL wild-card spot, is off Thursday and travels to Milwaukee to begin a three-game series on Friday.
Pittsburgh signed Bedard hoping he could stay healthy and regain the form that made him one of baseball's most effective left-handers from 2006-07 with Baltimore. He had no problems with his surgically repaired shoulder but had issues with his command.
Bedard walked 56 batters in 125 2-3 innings and let opponents hit .263, the highest batting average he's allowed since his rookie season in 2004.
Hurdle praised Bedard for willingly tinkering with his mechanics to try and find some consistency even if the results didn't follow.
"He cares, he competes," Hurdle said. "He appreciated the opportunity. Sometimes you all work in the same direction, you just don't get the right results."