You lose more ratings points drawing or losing to players rating significantly lower than yourself. That's why the top players cling onto being in the 'elite' circle where they get all the invites to the top tournaments. Those who haven't broken into that circle will likely struggle to keep their rating as consistent.
I think that worst case ratingdeal is to play players on the way up. Because upcoming players are underrated. Johan Salomon is an example. He is coming up, has a rating at ca 2350, but plays like 2450+. Or try Isak Sjøberg, rated at Norwegian 1249, or even worse, Isak in January rated at ca 1060. Isak may go above 1600 this year, so it is a very bad ratingdeal to meet him. He already passed 1600 in rapid, and actually is planning to get 2500 later.
Magnus will of course beat Isak, and probably Johan too, but Johan can play draw or even win.
The best ratingdeal is to play rusty highrated players that still has a high rating, but doesnt play as much as they used too.
Those super-GM´s are playing a lot of tournaments and keeping themselves sharp. It is very hard work to lure some ratingpoints from them.
The young Chinese players are coming up, they are a very bad ratingdeal.
Congratulations to China and Russia... and a brilliant showing by India.