For example the Mavs pick to OKC is top 20 protected till 2018, but if they have the 20th pick on a weak draft class (like last year) in 2017 while 2018 is looking to be a monster draft class (like this year), can they just say hey OKC, take our 2017's pick?
No, not unless the team holding the protected pick agrees to it. This might be in the form of a separate trade.
