Share is share of published decklists, not of the field. MTGO publishes exactly 32 decklists per Challenge, whatever the field size. A 448-player event gives the same 32 lists as a 32-player one. Those 32 lists lean heavily toward the top of the standings.
Leagues publish 5–0 decklists and no match data. Deck counts and shares count them, because a registered list is a registered list. Win rates cannot, because a League has no matches. So counts and shares cover all published decklists, and win rates cover paired events only.
Preliminaries contribute nothing. They publish match records but no decklists, so their matches have no archetype to attach to.
Win rates count only matches where both players published a decklist. The published 32 are the top finishers. Counting their matches against players who did not publish a list would push every archetype's rate up. With both sides counted, every win has a matching loss. So the pool always balances at exactly 50% wins.
