Laboy batted seventh in the inaugural game of the Montreal Expos versus the New York Mets on April 8, 1969, going 1-for-5 with 3 RBIs in the 11-10 win. [1] As a 29-year-old rookie, he excelled at the plate. His 145 hits gave him an average of .258, and he slugged 18 home runs and drove in 83 runs. He tied for second place with Al Oliver for the 1969 National League Rookie of the Year Award, which was won by Ted Sizemore.
In 1970, Laboy's average dropped from .258 to .199 as pitchers adjusted to him and stopped feeding him fastballs. However, he led the Expos with 26 doubles. Anxious to prove that his rookie year was not a fluke, Laboy worked out in the off-season but injured his knee in his first game of the Puerto Rican winter league season. The injury reduced him to 151 at-bats in the 1971 season and he spent most of 1972 on the disabled list after undergoing knee surgery in March.
At 33 years old and with essentially only two full seasons behind him it was hard to come back, particularly with the primitive state of orthopedic surgery at the time. He was released after the 1973 season and was not picked up by any other team. He ended his career with an average of .233/28/166 in 420 games. Exactly half of his RBIs were racked up in his rookie campaign.
Laboy returned to his native Puerto Rico and got a job with the government, where he served for 27 years, eventually becoming director of the Commonwealth's athletic programs.