I suggest if you watch the fight again do so with the sound off. The commentary is very bias in Khan's favor exaggerates everything he is really doing and completely downplays Garcia's work.
As the fight progresses you can see Garcia is working Khan out and catches his attacks better, his counters were getting better also and both the right hand and left hooks were landing. The key moment for me when I knew Khan was finished was the impressive body attack ,Khan could not deal with it and his demeanor changed when I saw that I suspected it was only a matter of time before he was taken out. The lucky punch excuse is pure myth. The way the story is spun is that Khan blew it rather than Garcia won it that is total garbage IMO.