I don't think Lucci is a top tier, but I do agree that this is a very casual fight for Zoro right now.
Lucci's still using his buff form, Awakening, and Haki.
All Zoro's using is Armament Haki and one sword right now.
And he's still got Lucci struggling to match his attacks.
I have Lucci in the low top-tier rankings, right around Yamato and... Croc, I guess?
Characters that can clear most of the verse and require an Admiral or Yonkou's full attention to be defeated. What the Shichibukai should be, really, the gap between Yonkou Commanders and Admirals.
This works really well IMO if you look at the original Warlords' strength:
1. Mihawk (Yonkou level)
2. Kuma (between YC and Admiral, closer to Admiral)
3. Boa (between YC and Admiral, closer to Admiral)
4. Doflamingo (between YC and Admiral, closer to Commander)
5. Jinbei (between YC and Admiral, closer to Commander)
6. Crocodile (between YC and Admiral, closer to Commander)
7. Moria (YC level)
This is actually a really functional group to deal with the four Yonkou.
Mihawk was known to match Shanks with two arms, so it's safe for the WG to assume Mihawk can handle him, at which point the Marines just need to deal with his crew.
Kuma is there to babysit Moria's dumb ass and take out Big Mom (Homies vs Zombies, Moria steals Big Mom's Shadow because Big Mom is... uh... easy to trick). Kuma's attacks can also bypass Big Mom's defenses, a lot like Law's. They honestly might not even need Marine back up here.
Boa and Jinbei work well since I legitimately don't think Jinbei would turn to stone from her since he's openly admitted he doesn't like her personality (THE GOAT), and Boa has way more respect for Jinbei than a lot of the other Warlord's because of Fisher Tiger. Kaido's crew is horny as hell: Boa low diffs everyone besides King and Kaido (maybe Jack). Boa's stone kicks neturalize King's defenses and slow him down, Boa takes out King while Jinbei holds off Kaido, then they tag team him. If Jinbei's in the water, this fight goes a lot easier.
Croc and Doflamingo are two peas in a pod, and both love murdering the old era. Crocodile knows how to fight Whitebeard, and Doflamingo is a nightmare matchup for Whitebeard because he can force Whitebeard's own sons to attack him. Doffy takes advantage of family ties and Pops' old age to have his own crew slaughter him while Croc and Marines handle the Commanders. (This isn't a Marineford scenario where Whitebeard has his entire fleet with him, just a few ships and his top officers).
If the original Warlords could... like, actually fucking work together, they WERE a legitimate counter-force to the Yonkou in theory, provided they had Marine support.
Lucci and Zoro should both be in the stronger than YC but weaker than Admirals tier, but both closer to Admiral. Same with Sanji.
The Wings of the Pirate King, whooooooooooooooo.