Granted, you have a point there.... I know you didn't suggest this, but I wanted to point out that Flacco played hurt (or is he?). It is not surprising when you have the offensive linemen and a long-developed (and rudimentary??) playcalling like ours, he is expected to get hurt. It is a matter of time before he is incapable of playing due to an injury, in my opinion. On top of that, he likes to hold the ball a bit too long, IMO.
Back to the OP, I understand the OP's point. Flacco does not have to scramble at every opportunity, but he should also capitalize on some opportunity to run and slide as a smart quarterback would. Tom Brady does that, and he is as durable as it gets (btw, Tom Brady missed significant games in a season for staying in the pocket, didn't he?) Last Sunday, he had at least two opportunities to run for a big gain, but he didn't.
With a linebacker spies on Ray Rice on every snap (I think it is one of the reasons why Leach was open on those short FB passes), there is a chance that a certain area of the field will be open. I don't care if it is a short gain, I rather a short gain than a sack and/or possibly a jarring hit that could knock Flacco out or a game changing sack/strip.