Here's an article I read early about Gronk's injury:
https://www.espn.com/nfl/story/_/id...nfl-playoff-picture-tight-end-future-2016-nfl
Some interesting points:
"The Patriots will surely keep him for 2017, even if he doesn't recover from the back surgery, because it would cost nearly as much money to trade or release Gronk ($6 million) as it would to keep him. It also would be nuts to move on from him this quickly, of course. If he doesn't recover to his prior self, though, the Patriots could cut or trade him before 2018 and turn that $11 million into $4 million in dead money. Knowing Gronkowski's injury history, they also could renegotiate that deal down to reduce Gronk's cap hit, as they did with Amendola in recent years. In other words, the Patriots have all the leverage. And given his injury history, that's a big deal."
As Grenouille said, Gronk's contract is a bargain for the best TE in football. But he's signed his contracts with his future in mind, going for guaranteed money sooner than a potentially higher payday later.
"While the tight end emerged as a star and was mostly injury-free before suffering a high ankle sprain during the 2011 playoffs, it became clear that Gronk (or his representation) was concerned about his long-term ability to stay on the field. It's hard to otherwise explain the deal he chose to sign before the 2012 season, just two years after entering the league. While reports at the time suggested that the six-year, $54 million deal was the biggest contract ever handed out to a tight end, the structure was incredibly team-friendly and contained just $12.9 million in guaranteed money.
Gronkowski got just that $12.9 million in cash over the first three years of his contract, which is staggeringly low. To put that number in context, the far inferior Jared Cook got $17 million over the first three years of his deal when he hit free agency the following season. Gronkowski's cap hit was 17th among tight ends in 2012, 21st in 2013, and ninth in 2014 before rising to second last year. This year, it's sixth in the league at $6.6 million, behind the likes of Jordan Cameron ($8 million), Julius Thomas ($7.3 million) and Kyle Rudolph (also $7.3 million)."
