Where are you getting that from? You may have a better memory than me so feel free to correct me but I don't remember her getting knocked down numerous times in her recent fights? (Forgetting the Rose one this is)
Joanna has taken on the four best by a distance in this division in her last four fights. Andrade hits like a fecking tank yet couldn't put her down, in fact Joanna dominated that fight. She got tagged numerous times by one of the best strikers in the division in Karolina and managed to withstand it and end up winning the fight only losing one round on the score cards. Gadelha has real power in the division and Joanna took the best she had to offer. Rose is the only one that has pulled it off.
Nobody can seriously sit there and try to tell me she has a suspect chin or fighters think that (maybe their attitudes have changed now they've seen her defeated, but prior to Saturday night). Joanna went to war with three of the best strikers in the division in Karolina, Andrade and Gadelha. She took plenty of damage and hits in at least two of those fights. If she had a suspect chin or it was her weakness, no chance she has fights like those and dominates late rounds like she did. It's just a very strange claim and only suddenly being spoke about after ONE loss. A lot of fighters would love to be able to withstand some of the hits she has and still perform how she has.