How good/important could he have been last year? He was out for almost half the season, and during this time the team didn't miss a beat. BB has already brought in competition for Edelman on special teams in the form of Washington. So, this should be a sign that there is no real LOCK of Edelman making the team. He'll have to compete for the job just like every other schmoe.
Edelman was a key piece in both the second Jets game and the Colts game last year. People forget, but Edelman's punt return against the Colts was the play that completely flipped the momentum of the game after the Colts had gotten out to an early lead.
Also, Washington is not one of the main threats to unseat Edelman on the team. First, obviously they play different primary positions and offer completely different skill sets on offense. Second, Washington is known for being a great kick returner. Punt returner, not so much. He's pretty much an average punt returner. If anything, Washington was brought in as competition / replacement for Jeff Demps.
Not saying he won't have to compete, but Edelman is clearly the best punt returner on the team. Anyone that wants to unseat him from that position will have to prove that they can be as dynamic.