Qualification rate is the most useful figure available for this game and it is also the one most often quoted without its denominator. A rate is qualifications divided by rounds entered, and both halves move for reasons that have nothing to do with skill: a player who mostly plays team rounds enters fewer rounds per show, and a player who plays during an event enters a round pool the ordinary rotation does not serve. Two rates computed over different pools are not comparable, however similar the numbers look.
The denominator also decides how quickly the figure can move. Early in an account's life a single show swings the rate visibly; after several hundred shows it barely moves at all, which makes a long-standing account look stable even through a genuine change in how well it is playing. Anyone reading a rate to see whether something improved needs it computed over a recent window rather than over the account, and the game does not offer that split.
There is also no way to separate solo entries from duo or squad entries in the published figure, and a squad qualifies or fails together. A player who mostly plays with others carries their teammates' rounds inside their own rate, in both directions.
Round type is the last confounder worth naming. Race rounds, survival rounds, hunt rounds and team rounds have different baseline qualification chances by design, because they eliminate different proportions of the field. A rate across a mixed pool is an average over those baselines weighted by whatever the rotation happened to serve, so it describes the rotation as much as the player.