User blog comment:Kaido King of the Beasts/Chapter 814: Mewl Like a Kitty, Bite Like a Viper/@comment-1595565-20160128190547/@comment-7890302-20160128205840

Actually, Zoro always was one of the smartest members. He almost always, when he actually puts the effort, points out the obvious. It's just he barely does so. If he actually applied himself, he'd easily be the third smartest Straw Hat member, and that's not bad compared to Ussop, Chopper (when Chopper doesn't act naive), Franky, Brook (When Brook acts his age) and Sanji, who are all rather intelligent. Hell, he is also more emotionally smarter then Nami, so that means Only Robin is smarter then Zoro.

Just, he acts lazy. So yeah.