A interesting topic, after reviewing/reading the article and current comments at the bottom, I thought of offensive style.
With BAL in particular they were a run first offense since that beginning of Flacco starting, RB Rice would be the setup man lulling the the D at times into sleep mode where they would be stunned by a deep pass. I suspect because most of the time as much I can recall, BAL O doesn't really play in catch mode. Catch up mode is when you're behind in points by at least 9pts, it would take two scores to get the win a TD and FG.
This year you could see BAL at times use the no huddle or speed up the game to get more touches of the ball (especially when OC Cameron was calling the plays), but in the playoffs they've reverted to run first in the first halves (with OC Caldwell play calling), waiting for the second halve to rely on Flacco's arm. Flacco I suspect hasn't had to run the offense from catch up mode as much as within one score mode. Those teams that get behind by 3 scores are normally doomed to lose and often throw a lot of passes and inevitably an interception occurs.
I think Flacco interception rate is low partly due to run first philosophy and also partly due to game situation/score for the majority of his career. If you don't have to play catch up you won't throw as many 'deep' passes or give the defense an opportunity to intercept the pass