Bullet players seem to be much stronger recently

Has anyone else noticed this? In the last week or so, my grade has plummeted and I don't think I'm playing any worse. My opponents simply seem much stronger than before at lower grades. I used to be able to slaughter 1300s but now I'm losing to people as low as 1200 who play accurate and fast games.

And I don't think it's cheating, players simply seem to be stronger now.

Thoughts?

The new league system gives bonus points for playing in arenas. It's also essentially a measure of how many hours you play during the week.

This means people will grind more hours of bullet arena which plausibly results in two things:

1) More of the people you're playing are not rusty. They've been playing a lot of bullet these last few weeks.
2) Some of the people you're playing are underrated. After a marathon session on Saturday their rating may have fallen 200 points, and now they're playing again on Tuesday, rested, and getting that rating back.

@llama47 Ah, thank you very much for this explanation that must be what it is. So I need to improve myself!