Gronkowski said in late December that he hasn't "been thinking about (retirement) at all," but Rapoport's sources believe he could end his career and potentially pursue options as a wrestler or actor.
The 2018 season was one of the worst statistical campaigns of Gronk's career. He caught 47 passes for 682 yards and only three touchdowns over 13 games. The five-time Pro Bowler has recorded 521 receptions, 7,861 yards, and 80 scores during his career over 115 regular-season games.
The 29-year-old toyed with retirement last offseason amid reports of the Patriots discussing a trade with several teams, including the Detroit Lions, Houston Texans, Tennessee Titans, and San Francisco 49ers.
Gronkowski and the Patriots then agreed on a restructured deal for 2018 that added $4.3 million in incentives to his contract before the start of the season.
He'll carry a cap hit of nearly $11.9 million for 2019 if he returns. Trading him would cost the Patriots $2 million in dead cap space.