You're basically giving the Patriots a another slot receiver that really wouldn't see that much playing time UNLESS Amendola or Edelman were to get injured. Braxton Miller with the Pats' second round pick and Kyle Murphy with their third round pick. You should really start doing some research on these teams before you make your picks.
Summary: Rivers is already one of the most talented scorers in college hoops. However, there are severals areas of concern about how he will transition to the next level, most notably his lack of strength, ability to play off the ball and defensive prowess. I think he would benefit from returning to Duke for his sophomore season but would likely be selected in the mid-lottery to mid-teens if he did declare this off-season.
Player Comparison: Monta Ellis. Ellis is only 6-3 but has become one of the most dynamic scorers in the NBA. Rivers is in a similar situation due to his size and lack of strength, but just has a natrual feel as a scorer whether it's attacking the basket or shooting it from deep. In fact, Rivers is probably already a better outside shooter than Ellis and has the ability to score at an elite level one day in the NBA.