Heh heh I find the pair quite entertaining... especially how Yachiru (pink hair) give directions to Kenpachi. If any of you haven't watched the 2nd OVA, watch it and see how bad Yachiru really gets haha.
But, I think the ranks as far as the 11th squad go aren't as you think, the strength is there. When Yachiru showed off her reiatsu while Ichigo and Kenpachi were fighting I think it proves she's quite strong, probably on level with Ikkaku. If she's hiding a Bankai, maybe even more. Ikkaku strength-wise seems properly placed at 3rd with his Shikai, aside from hiding his Bankai. Its just the pretty boy who wanted to be placed at a different seat, not the whole squad.