Not sure you can consider him a sleeper but he is a ways down the list of receivers...
Texas A&M WR Ryan Swope. He was the go to guy for Ryan Tannehill and was the go to man for Johnny Football. He projects to the slot but has the upside of a very good WR 2 with speed to be more than just an average possession receiver. If the Broncos don't plan on keeping Deck around due to cost, Swope would be a very smart pick in the 3rd round.