When the Expos became dissatisfied with Hubie Brooks‘s defense at shortstop, they called on this slick-fielding Puerto Rican. But Rivera hit just .205, and spent most of 1987 in the minors. After hitting .224 in 123 games in 1988, he was traded to Boston with John Dopson for Spike Owen and a minor leaguer. Used as a backup infielder, he hit better in 1989 than he had ever hit at any level. After two stints on the DL and a career low .208, the Sox let him walk to the Mets in February 1994, and he never again played more than 42 games in a season.