Mark Robson's The Harder They Fall is a terrific, tautly-made boxing movie (with fight scenes that blow over the pathetic stuff I saw in Requiem for a Heavyweight), and perhaps Bogart's best-ever performance--better even than his much lauded Treasure of Sierra Madre. There the material seemed beyond his grasp, and he flailed more than held us in his grip; here as sportswriter-turned-promoter Eddie Willis, turning a dunce of a boxer into a heavyweight contender, the material seems perfect for his low-key style.
This is the kind of sinking-into-the-depths-of-moral-depravity acting that William Holden got so many notices for in Sunset Boulevard, only Bogart here seems more washed up, more weary, yet more cunning with experience; when the slip begins, the descent is all the more harrowing becaue you know he should be smarter than that. Even when he faces off with his partner Nick Benko (a young and terrifically brash Rod Steiger), he makes the classic tough-Bogart remark, then backs down--precisely because he knows that's what the smart thing to do.
Perhaps his finest moment is when El Toro looks at Eddie, expecting money; you really feel Eddie's consternation, the conflict between guilt and avarice as he considers his choices. Bogart's entire performance and the story thus far has prepared for this--for Eddie to realize, to his dismay, that he has inconveniently grown a conscience. Nothing much happens, actingwise, but that's why Bogart is so perfect in it--he's a star, maybe on the downward descent at this stage of his career, making his last play as actor and artist, and he underplays magnificently.
The ending skitters on the edge of unlikeliness and crosses over, but again, Robson and Bogart sells the material (probably better than it deserves) by handling it with wonderful deftness--the whole thing revolves around Bogart's face as he, awkwardly and self-consciously, rolls the paper into the typewriter. He's about to play the hero, against all his instincts, and it's almost as much of a pain to bear as the guilt he had carried beforehand for so long.