The Bills moved up five spots to take Watkins at No. 4, sending the ninth overall pick along with their first- and fourth-round selections in 2015 to the Cleveland Browns in the trade.
ESPN reports that Marrone "clearly was not happy" with the trade since it did not involve a quarterback. Some sources recall him storming out of the room, while others recall him walking out.
Marone opted out of his Bills contract on Wednesday after two seasons with the team.
Watkins dealt with multiple injuries in 2014 but played in all 16 games, making 65 catches for 982 yards and catching six touchdowns. The 21-year-old led the team in receiving yards and touchdown catches.
Buffalo finished the season 9-7.
- Molly Geary