The Browns have much to prove after last week's scrum against the Steelers. Baker Mayfield, Odell Beckham Jr., Jarvis Landry, Nick Chubb and Kareem Hunt. Those are very good weapons and the Browns will turn them loose against a very bad Miami defense that just surrendered 37 points at home to the punchless Bills. 
Cleveland could very well run up a huge score in an effort to prop up their disappointed home fan base. 
I see the Dolphins contributing to this total going Over, too. The Browns almost have a JV defense minus suspended Myles Garrett and Larry Ogunjobi along with injured Morgan Burnett. 
Ryan Fitzpatrick is a good QB for an Over because he isn't afraid to throw downfield and is far more live than most QB's to throw a pick-six.