Actually no, not really. He continuously indicated that Zoro is the number 2, but not that there is a large difference, but still enough to keep that spot.
Sanji was there at the Kuma moment, however Zoro knocked him out and took the full brunt. There isn't a more symbolic way to make it obvious that Zoro is the number 2 of the crew.
Wadatsumi wasn't stronger, at least there is nothing that give that a sold basis. I mean Luffy pretty much beat Wadatsumi in one hit. I wouldn't call it a real 'beating' as Luffy just had to get passed him, but he didn't really had much issues with that. While Hyouzou, when Luffy hit him at the beginning of the arc, he blocked Luffy's attack. On top of that Hyouzou was the only one outside Hody Jones who went into that overpowered mode by eating those steroids. Wadatsumi was very huge and had a lot of brute strength, but overall he couldn't be really considered strong, not in the nature of Hody or Hyouzou, who had skills and techniques. Not to mention Sanji fought Wadatsumi with Jinbei. So it's pretty much invalid to say that Wadatsumi was the number 2 in the FI arc.
The Vergo battle is invalid likewise because in this arc the match up's were very unusual. Normally they are almost always perfect for the opponent they are fighting, but that wasn't really the case right now. For starters Sanji only had a brief skirmish with Virgo, it was not a 'final battle', you can't say he lost, but neither did he win. That was between Smoker, Law and Virgo. Neither was Zoro's fight normal as he fought together with Tashigi.
So neither of those battles work in favor of Sanji being equal to Zoro. Oda made it so that the difference isn't very large, but still that in the end Zoro is higher and the scene with Kuma more than anything else shows that that is the case. The fact that Sanji was there, but that Zoro knocked him out and took all the pain makes it pretty certain that Oda places Zoro a spot higher than Sanji.