There's one big difference. Keenum was mobile. Flacco is an equestrian statue. So, the sucky OL affected Flacco more than Keenum. That's a big reason why Elway went out in FA and got a RT. I expect him to draft some OL as well. If they want to run the ball effectively and protect Flacco, they need a great OL. Right now the OL is about the same as last year - add James, lose Paradis. Net of zero.
A lot will depend on whether Garrett Bolles can be trained to stop holding on every play.