Zhang didn't just get caught. It wasn't a one time mistake. She had gotten hit a lot by Joanna, proving there're many holes in her defense. Namajunas' team studied her and Rose masterfully exploited one of them.
People who thought the fight would be similar to JJ vs Weili are ignorant. Rose is far less hittable and hits much harder than Joanna. There was no way Rose in hell was going to stand and trade in a 5-round war. I predicted Rose would finish her within 2 rounds, because I seriously doubted Weili would endure getting hit by Rose a fraction of that. Unless Weili seriously improves her defense, there're other holes to exploit.
Not to mention that all Weili did was react to Rose's movement. She had no plan other than throwing leg kicks (weak ones, that weren't doing shit) hoping to hinder Rose's mobility in the later rounds. Rose dictated the way the fight was being fought and finished her without breaking a sweat.
Technical aspect aside, I think Rose has the mental edge over Weili. Even before fighting Andrade and Joanna, Weili said she wanted to face Rose, because she considered her the biggest threat. She probably wanted to prove she was better than Rose, but once she had Rose in front of her, she looked overwhelmed. Now she's making ridiculous excuses. After what Rose did to her, she'll probably be more hesitant and even scared going into the rematch. Fighters who are used to destroying their opponents are often never the same after being brutally finished.