The point values for winning or losing are calculated so that a rating of 0 will be right around 250th place(thus forcing newly submitted decks to enter approximately in the middle of the top 500). Because the point values required for this are dynamic and decks are constantly winning, losing, or being submitted, it may not be exactly in the middle but it should be very close. Therefore a deck which wins its first few games SHOULD be above 250th. As for something like a 10-2 record, this will depend on how strong the rest of the decks in the league are. If the average deck in the league has a 90% win rate, 10-2 would be well below that average and thus the deck SHOULD be below 250 for example.