"The thing that's impressive about Rob and Aaron, they're very bright, instinctive football players,'' Patriots offensive coordinator Bill O'Brien said. "They were able to pick up our system right away. And they each have very, very unique talents. To be able to copy what they do, though, I would say is much easier said than done."
It's a good time to be a tight end in the NFL. Rule changes outlawing hits on defenseless receivers and preventing contact beyond 5 yards of the line of scrimmage have made the middle of the field a fertile place for big, fast, athletic guys to catch passes.
A record 11 tight ends had 60 or more receptions this season.
"When you've got athletic tight ends like Rob, me, [the Saints'] Jimmy Graham, [the 49ers'] Vernon Davis and the like, who do you really put on them?" said Hernandez, who caught 79 passes this season and also has lined up as a running back. He's got eight carries for 70 yards in the Patriots' two playoff wins.
"It's tough if you put a linebacker on them because they're a little too fast for a linebacker. If you put a corner or safety on them, they're a little too small. You've got to have that one person who is like a tight end on defense. Like a safety, but more athletic than a safety and more physical than a corner. So it's tough to guard a tight end."
And if you've got two of them like the Patriots do, it's really, really tough.
"The biggest problem is matchups,'' Giants defensive coordinator Perry Fewell said. "If you take Gronkowski away, then Hernandez is open. If you try and take Hernandez away, then Gronkowski is available. If you somehow can take both of them away, then [slot receiver Wes] Welker's open. And [Deion] Branch."
"I've always liked two tight ends,'' said Brian Billick, a former Super Bowl-winning coach with the Ravens and now an analyst for Fox and NFL Network. "The thing two tight ends gives you is, what do you do defensively? Do you play nickel? Do you play base? I'm at an advantage either way, whichever way you decide to go. Everybody would love to have that configuration of tight ends if they could get it."
While the Eagles didn't use two-tight end sets nearly as much as the Patriots this season, it was a big part of their offense with Brent Celek and Clay Harbor. Of their 1,036 plays this year, 358, or 29.7 percent, were out of two-tight end sets. Almost 44 percent of their run plays and 21 percent of their pass plays came out of two-tight end sets. LeSean McCoy averaged 5.1 yards per carry out of two-tight end formations.
Celek had 62 catches, including 53 in the last 11 games. Harbor, who was taken just 12 picks after Hernandez in the fourth round of the 2010 draft, only had 13 receptions this season, but his role in the passing game is expected to increase next season.
"I don't know that either of them are at the level of Gronkowski and Hernandez,'' Billick said. "But they're both good, solid players. Clearly, that would put pressure on defenses. Particularly with McCoy. Because if you use two tight ends, you've also got to be committed to the run game to a certain degree.
"If a defense is going to put their nickel guys in [against two tight ends], you've got to be able to run the ball and take advantage of that. But there's got to be a commitment to it.
"If you look at New England, that's the thing that impresses me that [Tom] Brady has done. So much [of the Patriots' offense] is a check system. Tom says, 'Look, I know that I have this when I spread these guys out and I look like I'm in a three-by-two [three wide receivers, two tight ends] or three-by-one. But give me that right look in the box and I'm going to run the ball.' Their ability to run the ball in the postseason, their willingness to do it, has distinguished them."
The Patriots averaged 27.4 rushing attempts per game this season, which is pretty good for a team that finished second in the league in passing yards. In their 23-20 win over the Ravens in the AFC Championship Game, BenJarvus Green-Ellis averaged 4.5 yards per carry and had a 7-yard touchdown run.
Gronkowski, who is nursing a high ankle sprain that could limit his effectiveness, and Hernandez combined for 26 catches, 353 yards and four touchdowns in the Patriots' playoff wins over the Ravens and Broncos.
"This obviously wouldn't work if you had big, slow blocking tight ends and put them out wide and said, 'All right, run some receiver routes,' " said former 49ers and Lions coach Steve Mariucci, who now is a studio analyst for NFL Network.
"But the athletic basketball player-type, the athlete, the big receiver, is in vogue because it's hard for a team, any team, to carry enough defensive backs - cover guys - to cover these spread-out offenses like the Packers and Patriots play. When you have receivers and tight ends who can go out there, it makes it difficult to match up.
"Do you put a linebacker on that guy? Do you put a safety on that guy? Advantage offense. Do you put a corner, a little guy, on somebody like Gronkowski? Advantage offense. There clearly are matchup problems."