ther's an insurmountable wall between zoro and sanji, sanji can never fight on zoro's level, oda has seen to that.
-sanji: left brain tower
-zoro: outside right brain tower
zoro and king's power is so great that oda had to literally get them out of onigashima twice, extremely high level battle, not even the live floor could contain it (queen almost became collateral just from king losing his cool for a moment).
zoro and luffy are the only pirates that fought outside of the boundaries of the dome.
a clown like sanji has long been removed from the M3 dynamic.