I remember watching Von Miller sealing the edge when he had to. I also remember people thinking, at first, that he was washed up because he wasn't getting three sacks per game or something. I don't recall seeing him in coverage, but I wasn't looking for it either. I was looking for, hoping for quarterback pressure and much-needed run defense on his side.
While I didn't understand all the nuances of what I was seeing, it looked to me like he was playing the position.