"Let the search for Ben Roethlisberger's next mentor begin.

Bruce Arians, 59, the Steelers' offensive coordinator the past five seasons, retired Friday, throwing uncertainty into an offensive unit that is considered to have underachieved much of this past season.

Despite having one of the top quarterbacks in the league and a young, up-and-coming receiving corps, the Steelers averaged fewer than three touchdowns per game this season and ranked among the league's bottom third in offensive output. Their struggles were magnified against top defenses and could not carry the team past the wild-card round of the playoffs.

"I'm grateful to Bruce for his contributions and wish him nothing but the best in retirement," said coach Mike Tomlin in a statement. "I appreciate his efforts over the past five years for helping to lead our offense."

In choosing a new coordinator, the Steelers are likely to consider how a new offensive architect will handle Roethlisberger. The quarterback often vocally praised and supported Arians, whom he considered a friend. Arians, it has been argued, became too close to Ben and relied too heavily on Roethlisberger's arm rather than build a reliable ground game -- something Steelers president Art Rooney II asked Tomlin to resurrect a few seasons ago.

Arians could not be reached for comment yesterday. Tomlin's was the only statement released by the Steelers.

The Steelers likely will interview quarterbacks coach Randy Fichtner, partly because the organization historically has promoted from within. Arizona coach Ken Wisenhunt and Arians were Steelers position coaches before being elevated to offensive coordinator.

This time, though, the Steelers could hire an outsider, such as former Indianapolis coach Jim Caldwell, Green Bay offensive coordinator Tom Clements and former Kansas City coach Todd Haley."