You study is suspect.
I will try to be brief.
Memphis is listed in the city category because it's population is above 75,000 (criterion used for this particular list). Pine Bluff is below 75,000 and was not included in the list of Most Dangerous Cities.
The Most Dangerous Metro Areas includes Memphis and Pine Bluff because both cities are defined as Metropolitan Areas by the U.S. Census Bureau which is used by the FBI when compiling crime statistics.
The subject of the original post to you and to me was Most Dangerous Metro Area as you see below.
The U.S. Census Bureau defines Pine Bluff as a Metropolitan Area. If you don't like their definition, then tell them, not me.
The FBI compiles crime statistics. If you don't like their statistics, then tell them, not me.
I do think that you might possibly be looking at these lists of 'Safest' and 'Most Dangerous' as if they were the only definition for 'Quality of Life'. These lists use crime statistics as their criterion, and nothing else.