Heineman made his major league debut with the Marlins in 2019, and he he’s also had major league stints with the Giants, Blue Jays, and Pirates over the past few years. In total, he’s made just 283 plate appearances in the big leagues, and he’s hit .218/.297/.282 with one home run and a 66 wRC+. This year, he had a .237/.383/.316 line and a 107 wRC+ in 47 plate appearances with the Blue Jays.
The Mets are currently set to head into the 2024 season with Francisco Alvarez as their starting catcher coming off an impressive rookie season as a 21-year-old. Omar Narváez, who signed a two-year deal with the Mets before the 2023 season, figures to be his backup barring other moves between now and the start of the season.