If you are wondering why the Panthers didn't just wait for roster cut downs before giving up a draft pick Bill Voth has some good speculation:
Panthers Trade for Receiver Kevin Norwood - BBR
While Carolina could have waited for Norwood to be released sometime this week, the loss of Kelvin Benjamin and the current struggles of Corey Brown forced their hand. Plus, Norwood may not have fallen to the Panthers’ spot on the waiver wire. A fourth-round pick in 2014, Norwood caught just nine passes for 102 yards as a rookie.