Ricco worked in the office of the Commissioner of Major League Baseball, before joining the Mets in 2004. He became assistant general manager in 2006. When the Mets fired Omar Minaya as general manager in 2010, they named Ricco interim general manager. He served in the role from October 4 until October 29, when the Mets hired Sandy Alderson. When Alderson went on a medical leave of absence in July 2018, Ricco, Minaya, and J. P. Ricciardi assumed the duties of general manager. After the Mets hired Brodie Van Wagenen as their general manager during the offseason, they named Ricco senior vice president and senior strategy officer.
- Wagner, James. "The Mets Middleman Who’s Always on Call", The New York Mets, November 18, 2016. Accessed September 12, 2017. "Ricco’s path to the Mets’ front office began in a newsroom. Growing up in Cresskill, N.J., Ricco was a Yankees fan — an allegiance that has long since fizzled."
- Rubin, Adam. "Watch out Omar Minaya: Numbers man John Ricco could be next Mets general manager", New York Daily News, August 11, 2009. Accessed September 12, 2017. "Ricco, 41, joined the organization as assistant general manager in April 2004 after spending 12 years working for the commissioner's office at Major League Baseball.... A graduate of Cresskill (N.J.) High School and Villanova, Ricco wrote for the university's student newspaper."
- "Source: John Ricco won't replace Omar Minaya if New York Mets GM is reassigned". Sports.espn.go.com. September 13, 2010. Retrieved January 30, 2019.
- "New York Mets GM Omar Minaya relieved of duties, leaving team; manager Jerry Manuel out too". Sports.espn.go.com. October 5, 2010. Retrieved January 30, 2019.
- DiComo, Anthony (October 29, 2010). "Mets' future in hands of new GM Alderson". MLB.com. Retrieved October 29, 2010.
- Kussoy, Howie (June 26, 2018). "Mets GM Sandy Alderson is taking leave of absence to battle cancer recurrence". Nypost.com. Retrieved January 30, 2019.