Ryan Mallett starts at QB for Ravens

— -- BALTIMORE -- Ryan Mallett started for the Ravens against AFC North rival Pittsburgh on Sunday, becoming the team's fourth starting quarterback in six games.

The Ravens (4-10) signed the strong-armed Mallett 12 days ago, and the coaching staff has repeatedly praised him for his work ethic in learning the new offense. He was cut by the Houston Texans in October after being late for team activities, including missing a team flight to Miami.

Baltimore is turning to Mallett because he is considered the favorite to back up Joe Flacco next season. The Ravens had gone with Matt Schaub and Jimmy Clausen over the past four games, and they've combined for five touchdowns and seven interceptions. This comes after Flacco's streak of 122 straight starts -- the fifth-longest in NFL history -- ended when he tore two knee ligaments on Nov. 22.

Mallett, 27, hasn't started a game since he was with the Texans on Oct. 8, when he left after taking a shot to the ribs and never returned. He was 1-3 as a starter this season, with three touchdowns and four interceptions for a 63.6 passer rating.

This would mark the first time in the Ravens' 20-year history that they will have started four quarterbacks in a single season. Schaub will back up Mallett, and Clausen is inactive for Sunday's game.