ONe: YOu are running, I would wager, uptempo. SO is he. Meaning that there are more plays and will be more free throws regardless and more fouls. Second, every game is different from every other game. There end up being diferent substitutions, different people matching up against eachother. Probability doesn't work that way where everything is contained in a narrow band around the average. There will be SOMETHING that doesn't stay average in every game. THe mean does not mean that will even be the most common result, just the one that the results tend to cluster around. If they made the games constrain to that narrow of a band it would be VERY unrealistic.
Is this game
http://www.nba.com/games/20090202/SACPHX/boxscore.html"Unrealistic'? I'm sure THat SAcramento nor Phoenix average that number of free throws or fouls. DOes reality need to be adjusted because its not conforming closely enough to itself? YOu can find several games any given day that are wildly off what statistics woudl lead you to 'expect'