While he received coaching from professional pool players for the movie, including the legendary Willie Mosconi, the film's focus was on Cruise's natural talent and ability to learn the game quickly.
Cruise dedicated himself to mastering the techniques and nuances of pool, spending hours practicing and working with the coaches to ensure his performance was believable and impressive.
Therefore, although he was coached, Tom Cruise's innate talent and dedication were the real reasons behind his impressive pool skills in the film.