>>535735379
SF4 had hard knockdowns on a lot of common combo enders and on throws, which meant you had a lot of time to set up unseeable mixups and sometimes unblockables depending on the character. It usually involved jumping in at a specific spacing and timing to threaten an ambiguous crossup or empty jump low. Those mixups led into combos that looped the same knockdown situation, so players called that being stuck in the "vortex"