The Hawks have a high success rate against TE's, mainly due to the athleticism and speed of their LB's and Kam.
Teams that fail against Gronk are ones that play nickel and dime zone, and put slow LB's on him.........which allows Gronk to find seams down the middle and use his speed to run away from slower LB's, and size to out muscle nickel and dime DB's.
Hawks will bracket Gronk side to side AND top to bottom, like they have done against other great TE's.
The only TE that's had success against the Hawks this year was Gates, and that was because Kam was seriously hampered and Rivers dropped some serious dimes over the top of coverage. So while Brady might complete a couple great passes to Gronk into tight windows, it'll be few and far between.