Gilbride, the former San Diego Chargers coach, was hired before the 1999 season to help turn around slumping quarterback Kordell Stewart.
Stewart, however, wound up being benched last season, then struggled with his passing early this season before finally winning back the starting job at midseason.
Gilbride and Stewart clearly did not have a close working relationship, though Stewart never complained publicly about the complicated passing system Gilbride installed last year.
"I just wasn't comfortable with the direction we were heading in the passing game," Cowher said. "We were 29th in the league in passing when he got here and we were 29th in the league this season."
Cowher said there is no timetable for replacing Gilbride with what will be the Steelers' fourth offensive coordinator in five seasons. Chan Gailey left after the 1997 season and was replaced by Ray Sherman, who lasted only the 1998 season.
Gilbride, who had success as the Houston Oilers offensive coordinator, came to the Steelers a year after he was forced out in San Diego after going 6-16 in less than two full seasons as the Chargers coach.
Cowher, who coached the Steelers to a 9-7 season this year after two successive losing campaigns, did not rule out making any other coaching staff changes, though he said he had not definitively made up his mind.
Offensive line coach Kent Stephenson retired Monday after nine seasons, leaving running backs coach Dick Hoak as the only original remaining member of Cowher's first staff in 1992.
"Certainly there were a number of factors for this decision," Cowher said. "I wasn't comfortable with what we were doing in the passing game. We've given it two years to see some progress and I wasn't comfortable with where that was going.
"We ran the ball before Kevin got here. We ran it when Kevin was here and we'll run it after Kevin leaves, but we need to develop a passing game."
Cowher also wasn't happy with the lack of progress by the Steelers last two first-round draft choices, wide receivers Plaxico Burress and Troy Edwards.
Both were on the bench at season's end, and the two didn't combine for a single touchdown catch this season.
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