Batch, 35 years old and in his 13th NFL season, was inserted into the lineup Sept. 19 when Dennis Dixon injured his knee.
Dixon was filling in for Ben Roethlisberger, who is serving a four-game NFL suspension but is due to be back in the lineup Oct. 17 when the Steelers return to action after an off week.
Even with the makeshift depth chart at quarterback, the Steelers are 3-0. Batch was 12-of-17 passing for 186 and three touchdowns in a win Sunday over Tampa Bay. It was impressive enough to earn him the starting position for Sunday when the Ravens play in Pittsburgh.
"He is doing a nice job," Tomlin said. "We won last week. That is a good place to start. The guys have a great deal of confidence in him. He is simply a man that's taking advantage of an opportunity. You have to be happy for him."