On Wednesday, Boyd “Rainmaker” Melson (11-1-1) will face fellow New Yorker Jason Thompson (5-6-3) at B.B. King’s Blues Club & Grill on 42nd Street in a rematch of their six-round draw at Barclays BARC.LN +0.63% Center last November. That first meeting marked Brooklyn’s first major boxing event in 80 years, but Melson’s bouts are always about more than just sport.