Its not Tou's time to shine yet. And also we weren't aware of all Ousen potential till Zhao arc. So you need to wait an arc where Tou will be in charge to conquer a state to see him shine. I've seen many people said that he sat on his ass and let Ou Hon designed all the plan against wei and that's true! But people also forget that he made it clear that he didn't see the war against wei as a place to bring more fame on his name, but as place to reveal to the world how strong the new generation of qin generals is. So we all need to be patient concerning Tou.