The Title as a Promise
Every title makes a promise to the reader about the kind of experience they are about to have. A single-word title like 'Beloved' or 'Atonement' promises gravity and interiority. A title like 'The Girl on the Train' promises a propulsive contemporary thriller with a female protagonist in transit. A title like 'A Wizard of Earthsea' promises secondary world fantasy with a specific kind of protagonist. The promise does not have to be explicit, but it has to be coherent with what the book delivers. A title that promises one thing and delivers another creates a mismatch between reader expectation and reader experience, and that mismatch generates negative reviews regardless of how good the book actually is.