It's been beaten to death, but what sets Gronkowski apart is his rare combination of size and speed. He's too big to be covered by a defensive back, and too fast to be covered by a linebacker.
The tight end's big 6'6", 266-pound frame is ideal for winning one-on-one matchups. That size and wing span also make him a favorite target for Brady because when Brady makes the throw, Gronk usually makes the catch and has the reach to get to balls that defenders can't.
It's especially true near the end zone. Not only has Gronkowski raked in 18 touchdowns in 25 games, but he has also tallied five multiple-touchdown games in his career. That puts him seventh all-time in that category, and first all-time among tight ends.
Let's take a look at the two touchdowns he scored against the Jets as examples of why Brady loves Gronkowski more than any stripper ever could.
Patriots offensive formation: The Patriots line up in their favorite personnel grouping on offense, the "12" personnel, which consists of one running back, two tight ends and two wide receivers. This allows New England to field its four best offensive weapons at the same time. Tight ends Aaron Hernandez and Gronkowski line up on the offense's right side (at the top of the screen shot below), and receivers Wes Welker and Deion Branch line up on the left (bottom).
Jets defensive formation: The Jets line up with just two down linemen and two linebackers, with a whopping seven defensive backs. The formation, though, is what makes this set so interesting. Defensive back Kyle Wilson is at the line to jam Welker in the slot. Linebacker Aaron Maybin lines up on the line of scrimmage in a two-point stance. David Harris lines up between Calvin Pace and Muhammad Wilkerson, also in a two-point stance.
The Jets are in a Man 2 defense, with man coverage underneath and cover 2 over the top. With just a three-man rush, they drop eight into coverage. Jim Leonhard and Eric Smith are the deep safeties. By running this, the Jets get to have their cake and eat it too, with enough coverage over the top to prevent a big play (they think) and still use their signature man coverage underneath.
There is a small flaw in Man 2—there's sometimes an open space between the deep zone and the man coverage, and if timed correctly, there's enough of a window to sneak a pass in.
The defense jumps offsides, clearly off-balance and out of rhythm due to New England's hurry-up offensive attack. Brady knows he has a free play here, and reacts accordingly.
Inexplicably, Kyle Wilson turns around to look at Brady, and in so doing breaks off Gronkowski.
Eric Smith tries to compensate, but overcompensates toward Aaron Hernandez's side of the field, and ultimately trips over his own two feet trying to get back in position to defend the pass.
It almost looks as though the defense is expecting the official to blow the play dead due to the penalty, but they don't know what Brady knows—it's a free play.
Boom. Big touchdown by Rob G.
How did the other touchdown play out?
Patriots offensive formation: Second verse, slightly different than the first. Once again, the Patriots line up in 12 personnel with two tight ends and two wide receivers. Receivers Deion Branch and Wes Welker line up in the slot, and tight ends Aaron Hernandez and Gronkowski line up on the outside.
Jets defensive formation: The Jets line up in a favorite blitz package. They have three down linemen, three linebackers and five defensive backs in a nickel package with Darrell Revis lined up in the slot and Eric Smith shaded over Matt Light at the line of scrimmage. A safety lined up on the line of scrimmage, as it has been in the past, should be an obvious sign that the Jets are blitzing.
The route is designed to get Gronkowski behind the second level of defenders, and though Welker is manned up by Revis, his route is key in getting Gronkowski open. It pulls the best defender away from the football, and ensures that Gronkowski has a one-on-one matchup.
To that effect, we also see in the next photo that Danny Woodhead's underneath route is enough of a threat to lure linebacker David Harris up closer to the line of scrimmage, thus taking away any threat of an underneath defender creating traffic between the ball and Gronkowski.
The favorable matchup isn't all that hard to find. Just because Gronkowski doesn't usually line up on the outside, doesn't mean he's not a capable pass catcher when he's out there.
What's more, the guy who's covering him is Donald Strickland, a 5-10, 185-pound, 30-year-old defensive back. Brady will take that matchup every. Single. Time. Especially in the red zone, where Gronkowski can use his big frame to make tough catches.
Like this one.
So what do these breakdowns mean? It means you don't have to have a field-stretching wide receiver to have a lethal scoring option in your offense. Gronkowski's size makes him nearly uncoverable in the red zone or otherwise.
Yes, the two had 10 touchdowns last year and eight touchdowns this year, but it goes far beyond the red zone. Last season, Brady to Gronkowski was good for 42 completions on 59 attempts, 546 yards, 10 touchdowns and no interceptions for a passer rating of 139.5. This season isn't much different.
The numbers here are pretty incredible. Brady to Gronkowski has been one of the most efficient hook-ups in the league this season with a passer rating of 128.7, and that is largely due to the fact that Brady usually throws touchdowns and rarely throws interceptions when targeting Gronkowski.
That high number of touchdowns has made him a favorite target in the red zone, and the two have combined for 18 touchdowns in 25 games. It hasn't been all touchdowns for the quarterback-tight end tandem. The two have been getting it done efficiently since the second Gronkowski stepped onto the field.
Initially, it was his size that made Gronkowski such a favorite target for Brady. As he has gotten reps and gained some route-running savvy, he has gotten better at using that size to his advantage.
And it figures to continue, too. There simply aren't many linebackers left on the schedule capable of covering Gronkowski. Really, though, there aren't many linebackers in the league capable of that.
As he improves, the feat will only become increasingly more difficult. That should be a scary thought for opposing defenses and defensive coordinators.