It was harder to get into Diamond than it was to get into Master, for me. Have this clip from the previous round with this Chun-Li.

As much as I hate the sentiment that "Master" doesn't mean "good player", you can make it in there with some pretty big knowledge gaps, as you can see. This was the first Master I went up against, but since getting in I've had people lose to even sillier shit, myself included.

One thing where I was kinda lucky to have it click somewhere in the middle of Diamond was that I started tapping my parry button along to the beat of people's combos/blockstrings and that started giving me tons of bonus perfect parries overnight. Prior to making that minor adjustment I didn't really use my parry all that much outside of matchups with a lot of projectile spam.

TL;DR: Perfect parry is pretty good, and occasionally be willing to bust out the dumbest plays you can think of, cause people don't do well against wild playstyle switches.