Yes, despite Mandi being an excellent Defog user itself, it really dislikes SR up because at the end of the day it's still a wall, and hates losing 25% per switch-in. Most people know I'm a huge Mandi fan, but I'm pretty happy with as a solid A-rank. It handles Aegis and many physical threats very well and packs more utility than you can shake a stick at (Defog, Taunt, Whirlwind, Knock Off, Toxic, U-Turn, you name it). It has solid special bulk as well, but its unfortunate weaknesses cause it to struggle against a lot of top threats like Thundy, Greninja, Azu, Mawile, TTar, etc.
Regardless, it's hard to believe an A-rank threat was NU last generation. Who would've guessed?
A few other mons I forgot to comment on last time:
Azumarill -> A+. I simply forgot to mention my support of Azu last time, it's one of the scariest threats out there to any team lacking Megasaur.
Clefable is a pokemon that I absolutely love to use, it's amazing at so many different roles and has two incredible Abilities. It's probably won/turned around more games single-handedly than any other mon. My biggest hesitation with it is its low-ish base stats, which can make it difficult to function against the raw power of many OU threats even with Unaware. Still, I can see it boosted to A, because whether it's a late-game CM cleaner or a support/utility check, it's extremely good at its job. It's something I always remember to pack a counter for, and I think that shows it deserves a higher ranking.
Excadrill -> A-. It's obviously a huge threat inside Sand (or using Scarf), but Sand Rush Exca are very rare now (screw you Rotom), and without a boost its middling speed and common weaknesses really hold it back this gen. I've found that its support sets are often unable to switch into anything on offensive teams and get a spin off. Still a great Pokemon for a number of roles, but it has too many bad matchups to hang with the other big threats in A, I think A- is more suitable.
Gengar, Terrak (and Keldeo too I suppose) are all on the bubble of A- as well. Specs Keldeo is still extremely good though so I want to hear more arguments about that one!