Coaching, coaching, and coaching.
In the past 5+ years, whenever a seasoned veteran was either hurt, or lost to free agency, it seemed like the rookie/less experienced replacement was thrown to the wolves with opposing teams feasting on their rotting carcass. (NB: maybe with the exception of Crowell last year, but the defense still sucked with or without his contributions.) This year seems a bit different, as the current coaching staff seems to be able to acknowledge a players strengths and weaknesses, and set them up to succeed, instead of doing that square peg/round hole thing that the Mularkey/GW crowd seemed so adept at.