Former WBO junior welterweight champion Mike Alvarado, female fighting sensation Mikaela Mayer, and 2016 Olympic gold medalist Robson Conceicao will see action on the June 30 undercard at the Chesapeake Energy Arena in Oklahoma City. The card will be headlined by WBO super middleweight champion Gilberto “Zurdo” Ramirez’s title defense against Alexis Angulo and 140-pound … More Mikaela Mayer, Robson Conceicao and Mike Alvarado headline Oklahoma City undercard