Puig placed at least 900 bets through Nix-controlled betting websites and through a man who worked for Nix, authorities said.
In his plea agreement, Puig acknowledged lying in January to federal investigators who were looking into the business, denying he had placed bets through the operation.
Nix pleaded guilty in April to conspiracy to operate an illegal sports gambling business and filing a false tax return. Prosecutors said Nix’s operation ran for two decades and included both current and former professional athletes as clients or employees.
MLB would not investigate unless Puig attempts to sign with a big league organization.
Federal prosecutors also announced Monday that another former MLB player, Erik Kristian Hiljus, 49, of Los Angeles, had agreed to plead guilty to two counts of subscribing to false tax returns. They said he was an agent for Nix's operation.
Hiljus was drafted by the New York Mets in 1991 but made his major league debut in 1999 with the Detroit Tigers. He also played for the Oakland Athletics in 2001 and 2002. He pitched 124 innings in four seasons, going 8-3 with a 4.72 career ERA.
Hiljus could face up to six years in federal prison at sentencing.
AP MLB: https://apnews.com/hub/mlb and https://twitter.com/AP_Sports