Renpa at Zhao - 100
Renpa at Wei - 80 to 90
Renpa at Chu - about the same as Wei
It is a tier difference, yes.
It's a difference big enough that he has a chance against them, from that very position of Rinko & Genpo being killed and the HQ being taken. To having absolutely 0 chance.
But keep in mind, this is simply Renpa talking about it from that specific scenario. If Renpa and H4 had a Zhao army, Rinko/Genpo ain't dying on that battlefield. The HQ isn't getting taken. The fucking morale boost Kashibou/Rinko/etc would be giving these mfs would be insane.
Let alone the sheer Morale boost to the normal soldier from Renpa himself being in the front of it all. The Zhao army at Bayou had gotten a huge morale boost just from the FLAGS of the great heavens, due to what the 3GH mean to the Zhao soldiers.
Ouki was able to offset that balance provided from the flags with his ragtag army due to being there himself:
Ouki in that situation would've taken a L had Renpa been actually there, because it's a legit Zhao army, and they know what Renpa means to them. On the contrary to the Qin army, where yes they respect Ouki, but they're not legit soldiers like the Zhao army were.
It's a whole different ball game. It was the same with Ouki. Had Ouki been in charge of a legit Qin army and not a bunch of rag tags... it's whole different ball game.
While they weren't nerfed individually, they were nerfed through their armies.