There was a rumor that AJ was concussed going into the first Ruiz fight. Supposedly he got knocked out in sparring during his camp. I don't necessarily buy that but he did appear to be concussed after the first knockdown in the fight. He never recovered from it. His trainer, Rob McCracken, even
recognized that he was concussed but still allowed him to continue. McCracken got a lot of criticism for that decision and drew the ire of many in the boxing world. His only other option would've been to pull the plug on AJ.
You seem to think that Ruiz would repeat what he did to AJ in the first fight. Highly unlikely. AJ will outclass him again by boxing & moving like he did in the rematch. Ruiz will look like he's stuck in the mud which is exactly how he looked the last time. Did you see Ruiz's last fight against Arreola (aka Nipples)? Arreola hasn't been relevant in
many years yet he was consistently hurting Ruiz especially early on. He dropped him and then nearly dropped him again on a couple other occasions. Ruiz looked like ass. It's much more likely that AJ would box his ears off again if they fight a third time.