Difference between Rank and O-Rank
The "O-Rank" is an overall player rank based on current and prior seasons. Since it provides such a full spectrum analysis of a player's abilities, the "O-Rank" is the method used for determining autopicks in our drafts for Yahoo Fantasy Sports games.
The "O-Rank" is the best measure to use when comparing two players. It should be noted that the "O-Rank" only applies to default league settings.
The "Rank" value in our Yahoo Fantasy Sports games applies to the stats that you are currently viewing.
For example, on the "Players" page in your league, if you select Season Stats, the player rank value that is displayed applies only to their season stats (or season fantasy points in games use this system). If you were viewing last month's average stats, then the ranking value indicates how well the player played on average in a given day during the last month.
This rank gives you a sense for how well a player is performing over a selected time period (season, last season average, last week, last month average, etc.).