He briefly addressed the community assumption that placement in the new system would be the average of your current and top Elo and explained that the S3 seeding ratings aren't the same as the old, S2 rating thresholds.
"Wanted to clear up a couple misconceptions real quick:
There was an assumption that the formula was simply an average of current and top rating, but it was more complicated than that. We won't be disclosing the exact formula used for seeding. I can confirm that it did take top rating into account in a meaningful way.
The rating requirements for League seeding were not the same as the Season 2 requirements. They were determined automatically based on your position relative to the ranked population of your server. This is actually why we set everyone's medal to the provisional medal last patch; we wanted to indicate that 1500 wasn't necessarily Gold any more, and 1850 wasn't necessarily Platinum, etc.
I personally apologize for not making the second point more clear. I know a lot of you were expecting to get placed based on the numbers that you were familiar with and that didn't happen.
Using OP as an example, if you're in Silver I now and you've been at 1640 Elo during the preseason, you should have no trouble moving up to Gold. Consider it an early goal and soon enough you'll be seeing that awesome animation where the Silver medal turns into the Gold one. "
Hopefully that satisfies some of the questions you may be having about the new system!
PS: On a related note, I was placed into "Gold Division V of Xin Zhao's Emmissaries"; what fancy Leagues did you guys get placed into?