On the plain surface it looks like Greg Page should easily be able to outbox Mercer to a wide decision. But that didn’t always work out for him when facing equally matched or even lesser opponents. I remain uncertain
Page has the capability of winning based on his pure ability, but we never saw the best of Page, even against Coetzee, he was like 20lbs overweight, he should really have been like 215lbs or something: If we’re taking the best version of an existing Page against the best version of Mercer, then Mercer takes over mid rounds and wins on points. If Page ever got simultaneously in shape and motivated, he could win on points, but we’ll never know, as that version never existed.
Page and Mercer are quite similar in some aspects they could be very lazy they both lost to journeyman fighters Jesse Ferguson, Mark Wills. If we're talking strictly at their best I think the Page of 1983 could out point Mercer at his best Mercer has slow feet.