Jesus Fuck man! I believe the point of the story is that he's a stand up guy who fights whether injured or not. When fighting injured he doesn't make excuses and actually tried to hide the fact.
For what it's worth I've fought with a bad knee. Had three surgeries between the two. It affects your ability to plant, pivot, move laterally, even duck, bob and weave. You feel pain and weakness and it restricts normal movement. Doesn't mean he lost because of it, but depending on severity everything in the stand up would be off including timing.