With the kind of king he has Riboku is not really helped.
If the king had given even half of his army to Riboku they would have crushed the invaders.
And what kind of great general Riboku has : Houken who was beaten by MC Shin and was not there since the beginning and ShibaShou doesn't help outside of his city.
Imagine if Qin had done the same during the coalition arc : if OuSen or Tou hadn't wanted to help because they didn't want to move from their city. Or if Ei Sei didn't help during Sai fight = no more Qin.
The war is maybe in his own turf but Riboku has not a total advantage of it.
OuSen is good no doubt, very very very good but he didn't stomp Riboku tactical wise nor he was superior by a good margin as a general.
Without the 3 young 5000 commanders awakening that war would have been really different.
Riboku move killing Makou was really good for exemple. His counter pincer was good too.
OuSen really is amazing but he is not light ahead of everybody.
I think both sides have part truth to it.
Riboku army may have been declined help from Zhao king but can anyone claim his army numbers were less than Ousen Army? he had food supply problem? Or he had shortage of notable Generals under him?
At Yo Tan Wa side, she warded off Zhao 90k +Quanrong army with her 50k +10k Heki forces with not even bare mini food supply and enemy territory.
60k vs 150k approx(with other advantage)
At Shukai plains, Ousen had only 88k soldiers with Akou, Makou, Denrimi n So ou only experience Generals, with 3 young rising Commanders, and food supply disadvantage,
While Riboku had 120k soldiers, food supply, home territory advantage( he didn't utilise it tho), and Generals like Chau Ga Ryuu, Banaji, Gyou un, Kin moe, Gaku hi, Ki sui, Ba tei, Earl Kou, Earl Rai and GG Houken. And Kaine n Fu tei as commanders.
88k(4) vs Riboku 120k( 10 Generals)(food advantage)
I dont think Riboku had any disadvantage in this battle, and like Admiral Lee made a post on last week, Riboku made some good tactics in the battle and would likely have won the battle.
Riboku only lost due to Shin, Ou hon n Mou Ten awakening in the battle.
In Shukai Plains battle, Riboku was equal if not better than Ousen.
But Ousen has definitely beaten Riboku in the grand scheme of things, Riboku had no clue what Ousen plan was from start.