Ranking movers are calculated from recorded ranking snapshots. Daily compares the current compatible snapshot with a comparable snapshot around one day earlier; Weekly uses about seven days; Monthly uses the previous month; the year view compares with the first compatible snapshot recorded in the current calendar year; All Time uses the earliest compatible recorded snapshot.
PFA does not backfill imaginary positions. If there are not two comparable snapshots, the page says there is not enough history yet. New entrants are identified separately rather than pretending they jumped from the bottom of a ranking they were never part of.
Historical comparisons also use a compatible methodology version. If PFA materially changes the ranking formula, the version is stored with the snapshot so a later movement chart does not quietly compare two different formulas as though they were the same system.