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Well, what to begin with... first is that Sanji has been quite useless almost all the time.
For example in pre-timskip Sanji's role was always to be the smart guy in the room who always thinks one step ahead.
Sanji saved the strowhats in Alabasta thanks to mister prince.
Sanji saved the strowhats in Enies Lobby by closing the gates.
In the same Enies Lobby Sanji came up with the plan of how to save Robin when both Luffy and Sanji were running around.
Sanji did the same thing in woter seven etc. I can go on and on...
But in post-timskip Sanji is useless, not in his usual way that he always was.
Sanji is portrayed to be weaker in post-timskip.
Sanji hasn't defeated anyone in new world whiteout his raid suit.
The raid suit makes Sanji's fighting style useless, now Sanji is all about thecno strength. Etc. It needs a lot more explanation than I can give you here.
For example in pre-timskip Sanji's role was always to be the smart guy in the room who always thinks one step ahead.
Sanji saved the strowhats in Alabasta thanks to mister prince.
Sanji saved the strowhats in Enies Lobby by closing the gates.
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In the same Enies Lobby Sanji came up with the plan of how to save Robin when both Luffy and Sanji were running around.
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Sanji did the same thing in woter seven etc. I can go on and on...
But in post-timskip Sanji is useless, not in his usual way that he always was.
Sanji is portrayed to be weaker in post-timskip.
Sanji hasn't defeated anyone in new world whiteout his raid suit.
The raid suit makes Sanji's fighting style useless, now Sanji is all about thecno strength. Etc. It needs a lot more explanation than I can give you here.