There is no doubt that Lefty downplayed his injury to the detriment of the team. He could bearly throw but he refused to take himself out the game. But....if Heath Miller was the alternative, maybe that would have sent the "white flag" message to the Ratbirds. So it's really a tough call.
But..the real culprit in this is Tomlin for not having three QB's active. He knows the physicality of these Ravens/Steelers games and he knows how the injury bug keeps haunting us. Batch should have been active.