However, he also said starting quarterback Ben Roethlisberger, who missed two games with shoulder and rib injuries, began throwing Monday and could be healthy enough to play in the key game at Baltimore.
"We'll leave the door open for him," Tomlin said of Roethlisberger. "He's got a chance.
"Right now, Charlie Batch is our quarterback. We are working offensively to put together a plan to complement his strengths. That is our plan until otherwise."
The Steelers have lost both games since Roethlisberger was injured. Bryon Leftwich filled in against the Ravens in Pittsburgh but suffer a rib fracture in the game. Batch started last week against Cleveland, a game in which the Steelers had eight turnovers.
Pittsburgh is 6-5 on the season, three games back of division-leading Baltimore in the AFC North.