The Twenty20 Rankings work in a similar way to the established rankings for Test and ODI players. They are a weighted average, taking into account the strength of the opposition and putting greater emphasis on a player’s more recent performances. However there are several important differences in the way these rankings work compared to the ODI rankings, because T20 cricket is more about run scoring than taking wickets, and it is unusual for a team to lose all its wickets in this form of the game:
In addition to the above, all players who miss a match for their country lose 2% of their ranking points (compared with only 0.5% in ODIs). The reason for this is that T20s are so sporadic, often played in series of one or two, that any player missing a match could find himself waiting months for his next game.
A player will get a ranking as soon as he plays an international match, but players do not get a full rating until they have scored 600 runs or bowled 400 deliveries.