They clashed with BM's reinforced Zeus attack and casualy stopped it.
Meanwhile Zoro got zapped by BM.
What did Zoro so far? Waiting for a chance to sneak attack on Kaidou and not being able to damage him - besides with the magical Oden sword - which was just a scratch anyway. Not Kaidou nor BM give a shit about Zoro, but his sword. This is what you swordsucker call ''Zoro is fighting Yonkou's''?