I play kasumi and have the same problem you do playing aggressive players. They get in my face and constantly attack my guard over and over again and I cant do anything about it. I know I cant block forever or else ill get thrown so I try and throw or throw out her 11 frame mid when I see an opening, only to get stuffed and end up being stunned.
Im guessing its the terrible netcode. I feel like most of my matches are one big counter stun fest. They either stun me while im trying to slow them down or I get lucky and my attack crushes and I get the stun. It doesnt matter how many bars my opponet has 4 or 1 every match I play has lag spikes in the middle of matches or feels slowed down.