Oh please stop with that Kenpachi fanboying.
These quincy that are invading SS right now are the beings that stand the closest to Ichigo's post dangai training powerlevel and I'll dare to say that each and every one of them is at least as strong as Yama in shikai (Yama being obviously much stronger with his bankai but in a situation where he cannot use it).
Kenpachi had problem to deal against Noitora's strength, he's a tank but the fucking 5th espada's hit were hard enough for him to understand that he should not be hit by them anymore and these Quincy are in a position to hit much harder than any Espada ever did, actually probably hit even harder than what Aizen used in his last transformation stage.
These Quincy demonstrated currently unrivaled speed feat (Stark was the fastest espada and even him couldn't speedblitz Kyouraku as much as that Quincy just did).
Quincy are also Kenpachi's nemesis. They excel in keeping a distance and nuking anything far from them, Kenpachi doesn't have the speed necessary to close the gap so he would just take hit until he die.
Yama can hold on, Shinji probably can because of the ability of his shikai but not because of his physical capabilities and Ichigo is the only one in a position to destroy the invaders with raw physical capabilities.
The question is how long can they hold on? Because as long as Ichigo isn't here they are doomed to get killed.