Mercer by KO, probably. A replay of the Mercer-Morrison fight, except Shavers won't take a many consecutive puches as Tommy did before caving in.
Earnie could win, if Ray had an Off-Night, but most likely Mercer stops Shavers in 9 rounds, somewhat like Cobb did.
I agree with Magoo that it's a bad match-up for Earnie, but, yeah, 'Which Mercer?' is the question, despite the clash of styles and attributes being in his favour.
Mercer withstands the hardest punches in the universe and comes back to KO a gassed Shavers. Just watch the Lyle - Shavers fight, a rerun of that fight.