Gronkowski has been dealing with a back injury that locked up on him ahead of Week 7's contest against the Chicago Bears. The tight end played in last week's win over the Buffalo Bills, but isn't healthy enough to go against Green Bay in a battle between Tom Brady and Aaron Rodgers. The importance of his absence needn't be explained in an offense quarterbacked by Brady.
Though not in the headline, another key inactive for the Patriots is guard Shaq Mason, who is having a solid season at the position and would've been an asset against Packers defensive tackle Kenny Clark. As is the case with all quarterbacks, pressure up the middle is the worst kind for Brady, making Mason's absence (and the performance of his replacement, Ted Karras) an important one in the prime-time affair.