The Fair buff does not compensate for the nerf at all, only 4 frames? Nope not enough no matter how much positive energy and optimism others put into it. Its a cute present, if another patch comes they should expand on this new direction they want to take MK. He'll dip hard in japan so hopefully he's under Ike, in whatever tier list they make.
How much worse he's gotten is unknown, but he's not as strong or stronger than Pre patch MK who wasn't even fully optimized. His representation has naturally taken a nose dive, the ones who's staying such as Leo,Tyrant(maybe) and Ito(maybe) will not solo MK they have secondaries such as Diddy,Fox and Cloud. They want to win after all.
MKs appearance will be like the good ol dark age of customs/solid mid tier. Don't expect to see him at tournaments, his presence is gone in the meta but then again its only been roughly 2 days. If a character got bodied by uair combos they still do, Samus,Kirby,Peach,Rosa,Pit,Zelda,Jigglypuff. Characters that died below 20% in the first place. They die before they reach the %s where they tumble, heavy weights also go into tumble late so they might suffer still. Requires proper testing.