The O-line isn't as bad as people make it out to be, a lot of the sacks are Roethlisbergers fault. He holds on to the ball way too long and tries to make a play when nothing is there. However, this is also the reason he is so good, he makes plays no other QB can make, but he also takes more sacks then any other QB.
Edit: Yeah Flacco is overrated because his rookie year, but he should still benefit from Boldin.