Actually, Karen's PB is 199, so Ashley is the only US lady with a PB higher than Polina's. But otherwise, I agree.
Wait actually, I just checked and Polina's official ISU PB is 187. Are you using domestic numbers/senior B numbers?
Yes. I'm using numbers from Nationals as well as international--not a good measure of how our ladies do internationally, but valid when talking about Nationals.
Since Bradie Tennell's the only one who's broken the 200 mark this year internationally, I don't see her getting bumped. Realistically, she skates anywhere near how she's been skating at Nationals and she'll blow past Polina's PB.
I know Mirai's a fan favorite, but she's going to need to perform to get on the team, I don't see her as a sure thing at all. I don't think the judges, at this point, will give her the benefit of the doubt.

