I always interpreted it as the physical result obtained whether you either:

- miss the shot by a hair and hit something unintended instead
- choke your mentally intended shot by a mile and send the ball god-fuck-knows-where
- make the shot perfectly but have the game mockingly spit the ball back in your face

....In all cases, you might well achieve the same negative outcome by flipping a brick instead of a ball.

Alternatively, I have always referred to the "brick shot" as that last, unusually potent brick-to-face swig or two at the bottom of the bottle