1. A method comprising: monitoring stream data associated with a subscriber's usage of a network resource for a predetermined time interval for developing a flow-accumulation history; deriving, from the stream data, byte data associated with the subscriber's usage of the network resource for the predetermined time interval for developing a byte-usage history; applying an outlier detection logic to the byte-usage history; assigning a byte-usage band to the subscriber based on the outlier detection logic as applied to the byte-usage history; applying the outlier detection logic to the flow-accumulation history; assigning a flow-accumulation band to the subscriber based on the outlier detection logic as applied to the flow-accumulation history; assigning an overall usage-band to the subscriber based on the byte-usage band assigned and the flow-accumulation band assigned; and applying a mitigating action to the subscriber based on the overall usage-band assigned.