What caused Tall Boy to look crushed and beaten?

Tall Boy looked crushed and beaten after his spear failed to take down the leader of the Long Knives. His failure caused his family and the people of his tribe to be captured by the Long Knives.
In Chapter 16, Tall Boy's people decided to take a last stand against the Long Knives. Despite his injury, Tall Boy insisted on being part of the effort. Although his right hand was now useless, he felt that he could do justice with his left one. He had been practicing with his left arm and was confident that he could do his part to take down the leader of the Long Knives.
However, when the moment came, Tall Boy's lance missed its target. Instead of flying straight towards the enemy, it "wobbled and then curved upward," striking the branch of a tree and then falling broken at the foot of the leader's horse. This was a humiliating moment for Tall Boy. When he ran past Bright Morning, he "no longer looked like a warrior." Instead, he looked "crushed and beaten," a shadow of his old self.