Brock Lesnar's UFC Paycheck Is Key to Cormier Fight, Says Paul Heyman

[[tmz:video id="0_lrw69jdm"]] Brock Lesnar's personal "advocate," Paul Heyman, tells TMZ Sports ... the only real thing standing in the way of a UFC fight with Daniel Cormier is the size of his paycheck. Of course, Brock and DC have been…