Zoro was injured fatally thanks to Kuma in TB while Luffy was fully healthy and Sanji was pretty fair in health. Zoro couldn't really go all out thanks to that. Hell that's an extreme Haki bloom if you think about it.
Zoro has been training with the WSS longer than Luffy trained with Rayleigh, Zoro trained with a teacher that is nearly identical in his fighting style while Luffy could only get basic haki training from Rayleigh. Unlike Luffy who just kept fighting animals, Zoro already beat all the Baboons on his 1st day, and the only one left to train him was Mihawk, a legit Top Tier. It's not that Zoro is skipping levels. It's the fact that Zoro came out of the timeskip immensely powerful, and in my opinion at this point way more powerful than Luffy.
Being a MC doesn't make you more powerful than your allies just because.