Boss Bai told Li Yao that, based on his knowledge in the past and his recent contact with Yun Xuefeng, and especially after analyzing the guy's battle cases in the Imperium's counterattack, he realized that while the guy was not a useless general, he was hardly an eminent general either. At best, he was a qualified commander with enough experience.
The problem was that the consecutive victories in the Imperium's counterattack filled Yun Xuefeng's head with illusions and arrogance. He was truly under the impression that he was a general on par with Lei Chenghu and had been competing with him whenever possible. When Lei Chenghu openly joined the reformists, he even declared that he would meet Lei Chenghu in a space battlefield someday so that it could be decided which one of them was better.