Of the $4.3 million, Gronkowski can earn $1 million in per-game roster bonuses. Then he can earn a maximum of $3.3 million by hitting three of the following four incentives, according to Rosenhaus:
• $1.1 million for 70 or more catches
• $1.1 million for 1,085 receiving yards
• $1.1 million for 80 percent playing time
• $1.1 million for nine or more touchdown catches
Last season, Gronkowski finished with 69 receptions for 1,084 yards and eight touchdowns, with 79.3 percent playing time.
By structuring the deal in this manner, Gronkowski's salary-cap charge for 2018 won't be dramatically affected, as the $3.3 million in incentives won't increase the charge.
This marks the second consecutive year that the Patriots have added incentives to Gronkowski's contract. The team did something similar with quarterback Tom Brady earlier in August, adding $5 million in incentives to his deal.
Last year's contract sweetener gave Gronkowski a chance to increase his earnings from $5.25 million to $10.75 million, according to Rosenhaus.
Gronkowski still has a base salary of $8 million for the 2018 season. His contract extends through the 2019 season, when his base salary will be $9 million.
Asked Tuesday about his hopes for a sweetened contract, Gronkowski said: "I'm always open for that. That's not really my focus. I got a long season ahead and just trying to focus on what I need to really do and just let everything else play out."