i don't agree with Ousen's explanation.
Surely losing Chou Ga Ryuu and Gyou'un is regrettable but that was far later and those 2 belongs to the right wing.
The left wing suffered almost total collapse due to their commanding general was slain and Mou Ten barely able to hold them together to buy time which in itself is almost ridiculous judging that the Ki Sui army not only number superior also got more food and 2 talented commanders (Ba Tei and Ki Sui). Later on, even Shin was moved away from the left wing so only Mou Ten and an army of half its strength to hold its own with Ba Tei and Ki Sui.
For the Right Wing, Zhao got at least 3 noticeable generals Ba Nan Ji, Chou Ga Ryuu and Gyou'un. It was almost miraculous that The Young-Star team of Ou Hon, Shin, Kyuu Kai with the help of Akou and A Ka Kin.
If you notice, Shin and possibly Kyou Kai appeared in all 3 fronts but there are lagged of time between these period, the Qin Army is always outnumbered both in soldiers and talented commanders. Yet The fact that Ri Boku army haven't done anything of value during this campaign is questionable.