Either

How many times they had either a 300+ yard passing game and / or a 2+ touchdown game.

Variance (Standard Deviation)

This reflects the differential of how many points a player scores vs the player's scoring average per game.

Shake (Coefficient of Variance)

To further emphasize consistency, simply divide that average variance by the player's points per game. This gives a percentage between 0% and 100%. 0% is perfectly consistent, while 100% is completely inconsistent.