The extrapolation is where it all goes wrong. There's no such thing as "infinite number of shots"... Time is a very, very important part of the equation. All players have to perform within a specific time frame.
The whole "if we extrapolate X to 1,000,000 samples" is fantasy. Matt Bonner won't take more than 2-4 3s a game, and that's the chance he has to make an impact. And it isn't just him. Every player has a window of opportunity to produce. This is further subdivided into regular-season (less important) and playoffs (more important).
Take this series. He's currently 1-7 (14%). Let's say he finishes the series 2-10 (20%)... If the Spurs season is over, it really doesn't matter if he statistically evens out the next regular next season over the first 5 games or so... we needed his production in this series.