The Mercer that Lennox fought would have Joyce in Hell. That chin, the quick combinations with power on them, someone who's not gonna fold.............And I'm not sure but I never remember anyone being able to walk down a prime Mercer (if I'm wrong please expand on that) which Is Joyce's primary tactic, pressure til the pipes burst.
That version of Mercer would have most fighters in hell. If I recall correctly, Mercer wanted to fight Tyson during that era and Tyson noped the hell out of there.