Shot Difficulty On-Off Data for all players

ShotValue is simply Shot Difficulty * the point type of the shot (i.e. 3 for 3 point shots or 2 for 2 point shots). AvgShotValue is the average for the player. Shot Difficulty was introduced here: http://nyloncalculus.com/2015/05/13/introducing-shot-difficulty-comparing-game-winning-shots-in-the-playoffs/