i apologize if this sound weird to you, but recently i was checking standings of recent contests. and i noticed that many 1680 something rated people were getting -ve rating change even at ranks like 1100, if i am not wrong just 3-4 contest earlier this rank was good enough to cross 1750.
Also specialist around 1550 are not able to become expert even at ranks like 1500,
is the participation some factor? or maybe codeforces change something internally?