The world worships excellence and runs on mediocrity. Most of us are fated to dwell in the fat middle of the bell curve, admiring and envying those who stake out territory in the higher realms of achievement. There is a wide gulf between doing your best at something and being the best at it, a discrepancy in expended effort and anticipated reward that is the subject of “Whiplash,” Damien Chazelle’s thrilling second feature. This story of an ambitious young striver and his difficult mentor could easily have been a sports movie, and structurally, it resembles one. There are montages of grueling practice scattered among scenes of tense competition, all of it building toward a hugely suspenseful (but also, to some extent, never in doubt) championship game moment of reckoning. But Andrew Neiman (Miles Teller) is a jazz drummer rather than an athlete, enrolled at a highly selective Manhattan school (Juilliard in all but name) and under the sway of a charismatic and terrifying instructor, Fletcher (J. K. Simmons). Fletcher has a first name, but nobody has the nerve to use it, and in classic drill sergeant or gym teacher fashion, he calls his students by their surnames, generally in the course of browbeating and humiliating them. Progressive pedagogical methods have not penetrated the room where his studio band practices, a virtually all-male preserve of sarcasm, sadism and enforced virtuosity. There is nowhere Andrew would rather be. — A. O. Scott