The nightmare scenario just came true for the Patriots. Given how well Jimmy Garoppolo played during the first two games of the season, you might be able to make a case that Rob Gronkowski was New England's most irreplaceable superstar. The Patriots will be forced to find out whether that's true, as Gronkowski will undergo surgery for a ruptured disk in his back on Friday. The injury will likely end Gronk's season after just eight games, 25 catches and three touchdowns, though the team and Gronkowski's family said in a joint statement that they wanted to wait until after the surgery to make a "final determination."

This has to be a shock to the Patriots, who used their lone injured reserve/designated to return slot on Jacoby Brissett earlier this week when they obviously would have spent it on Gronkowski if they thought he would require surgery or had a chance of coming back. There's nothing the Patriots can do about the injury, and there's no sense crying over spilled milk. What's important now is figuring out what's next -- for the Patriots, Gronkowski and the rest of the NFL. Let's start with New England, which suddenly has a crater-sized hole in their path to the Super Bowl ...

What's next for the Patriots?

This is not uncharted territory for the Patriots. Gronkowski already has missed three games this year and played a limited role in two others. He hasn't played a full 16-game season since 2011, though Gronkowski made it through 15 games in 2014 before sitting out a meaningless season-ender in Week 17. The idea of having to definitively plan for a short-term (and possibly a long-term) future without Gronk is unfamiliar, though; this is the first serious injury the likely future Hall of Famer has suffered since 2013, when he tore his ACL and MCL in a collision with then-Browns safety T.J. Ward.

The strength of the Patriots' offense, especially over the past decade under the on-again, off-again stewardship of Josh McDaniels, has been its ability to change its shape. Having Tom Brady helps, of course, but we saw how effective the offense could be during the first three weeks of the season, with Garoppolo at quarterback and Gronkowski either out or a shell of his usual self. The Patriots have managed to transition from a spread attack with Randy Moss and Wes Welker to the two-tight-end sets of Gronkowski and Aaron Hernandez to an offense that incorporates both. They've overcome subpar offensive lines and managed to get the most out of players other teams weren't interested in, such as Julian Edelman, Dion Lewis and Martellus Bennett.

Bennett looms large in how the Patriots will handle the Gronkowski mess. The goal for this year was to build an offense around the twin terrors of Gronkowski and Bennett, who would be able to stay on the field and dictate mismatches regardless of the defense's personnel choices. Injuries have prevented them from ever really pulling that off. By the time Gronkowski made it back from his hamstring injury, Bennett got hurt, suffering an ankle injury in a three-touchdown performance over the Browns.

Bennett has averaged 38 receiving yards per game without scoring a touchdown since, and he has continued to miss practices with ankle and shoulder injuries. The Patriots surely would have loved to rest Bennett down the stretch to get him fresh for the playoffs. Now he's going to have to play through the pain the rest of the way. Even worse, just as was the case when the Patriots turned to Garoppolo, losing your starter also means you're one additional injury away from lining up replacement-level talent in a key role. The Patriots were forced to turn to Brissett, the third-stringer, when Garoppolo went down after two games, and while he got by against the Texans, he was a mess against the Bills in New England's first loss of the season.

Now the Pats are one aggravated ankle from an empty cupboard at tight end. They traded A.J. Derby to the Broncos for a fifth-round pick in October, a move that seemed smart at the time but has now gone sour for reasons the Patriots could not have realistically projected. The only other tight end on the roster is former Northeastern product Matt Lengel, who has six career snaps to his name. There are no real options on the waiver wire either, with Scott Chandler out after undergoing offseason knee surgery. The only logical fit might be Zach Sudfeld, who was last with the team in 2013.

Rob Gronkowski hasn't played in all 16 regular-season games for the Patriots since 2011. Maddie Meyer/Getty Images

Last week, the Pats used backup offensive lineman Cameron Fleming as their second tight end for 15 snaps, which obviously offers little utility in the passing game. One of the ways to move on from Gronkowski might be to rely more heavily upon the running game, but Gronkowski's absence makes that harder to pull off too. The threat of Gronkowski running up the seam is enough to keep safeties off the line of scrimmage, and his success as a pass-catcher has left him as a criminally underrated run-blocker. I wrote about his role in the running game in 2015 before the Colts-Patriots AFC Championship Game, and Gronkowski has been a huge part of why the Pats have been able to run all over Indianapolis at will in years past.

Schematically, the Patriots will likely get away from their two-tight-end sets and shift their base offense toward three-wide-receiver formations, with Danny Amendola and Malcolm Mitchell getting more snaps. Mitchell and Chris Hogan, in particular, will need to threaten teams downfield more frequently with Gronk missing. Mike Reiss noted yesterday that the Patriots have begun to experiment with a "Pony" grouping, which includes a pair of receiving backs in James White and Lewis. It wouldn't be a surprise to see the Patriots try to use that grouping more, perhaps in sets with no tight ends, in the hopes of forcing opposing linebackers into a matchup they can't win.

The place where the Patriots will miss Gronkowski most, of course, is in the red zone. Research I conducted before the season suggests Gronk was the best red zone weapon in football on a per-play basis going back through 2006. You've seen Gronk play. You don't need me to tell you he is good in the red zone. The Patriots have actually not been notably great in the red zone this year; they're third in offensive DVOA but just 12th in points per red zone trip, a number that isn't likely to drastically improve without Gronkowski around.

Another "kowski" looms larger than usual now. If the Patriots do struggle in and around the red zone, it will be critical for Stephen Gostkowski to make sure their drives end in successful field goals and extra points, and he has struggled mightily this season. Gostkowski already has failed on three extra points this season and has missed more field goal attempts in 11 games in 2016 (four) than he had in any of the three previous seasons (three or fewer). The normally reliable Gostkowski has been the 12th-worst kicker in the league this year on scoring plays. With Gronkowski gone, they need the old Gostkowski back.

The margin of error for everyone on the Patriots, actually, is dramatically reduced by the Gronkowski injury. An offensive line that has been better this year after the return of legendary offensive line coach Dante Scarnecchia needs to keep things up; right tackle Marcus Cannon, in particular, can't revert to the guy who made Patriots fans groan before an impressive 2016 season. The Patriots' pass defense, a dismal 28th in DVOA heading into this week, can't allow the likes of Ryan Fitzpatrick to post 115.2 passer ratings.

And of course, as it always does, it comes down to Brady to elevate his game without his best receiver around. As Chris Wesseling of NFL Network noted in November, Brady has been a superstar with Gronkowski and basically a league-average passer without him. Here are Brady's numbers since Gronk entered the league in 2010 in games with and without his longtime tight end. I'm also putting the 49ers game on the latter side, given that Gronkowski played just seven snaps before leaving:

Brady's Numbers With/Without Gronk Split Cmp Att Cmp% Yds Y/Att TD INT Rating With Gronk 2,044 3,116 65.6% 24,722 7.9 189 39 104.8 Without Gronk 412 714 57.7% 4,663 6.5 32 13 84.7

The average passer rating for the league as a whole since 2010 is 87.0. It puts Brady in a range with the likes of Kyle Orton, Michael Vick, Joe Flacco and Sam Bradford, all of whom have passer ratings between 83 and 86 over that time frame. It's true that every quarterback will look worse without his No. 1 weapon, and it's entirely possible that Brady and the Pats are better-equipped to handle Gronkowski's absence this time around with Bennett.

It's also very clear that Tom Brady is not Tom Brady without Rob Gronkowski. Remember who Brady goes to when the chips are down. As much as he trusts Julian Edelman, it was Gronkowski who Brady threw to on fourth-and-the-season twice against the Broncos in the AFC Championship Game last season, even though his tight end was double-covered on both occasions. They simply aren't the same team without him.

What's next for the rest of the league?

In the short term, very little should change for the Patriots, who are huge favorites to win the AFC East. At 9-2, their closest competition is the 7-4 Dolphins, who have won six straight games with the past five coming by seven points or fewer. FPI gives the Patriots a 97.7 percent chance of winning their division, more than any other division leader. Even if their true team strength drops with Gronkowski and FPI can't yet realize that, the Patriots have a two-game lead and the tiebreaker on the Dolphins with five games left.

This should really benefit the trio of contenders in the AFC West more than the Dolphins or Bills. The Patriots currently have a 68.5 percent chance of coming away with the top seed in the AFC, per FPI, even though their 9-2 record is identical to Oakland's. The Raiders are in second at 22.8 percent, mostly thanks to concern about their end-of-season slate, with three road games to come against their AFC West brethren. If the Chiefs beat the Raiders next Thursday and move into first place in the West, they would suddenly be a threat to the Pats, given that the Chiefs would then be 7-2 in the conference, lurking just behind the Pats, who are currently 7-1 in those games.

The Raiders, who are battling with the Patriots for the AFC's No. 1 seed, stand to be one of the main beneficiaries of Gronkowski's injury. Kim Klement-USA TODAY Sports

Meanwhile, the Broncos play the Patriots in Denver in Week 15, and Gronkowski's absence might be enough to turn coach Gary Kubiak's team from slight underdogs in that game to slight favorites. The Broncos don't need that victory to make the playoffs from where they are now at 7-4, but it's also the toughest remaining game on their schedule. They have road trips to Jacksonville and Tennessee coming up; if they can win both of those games and then beat the Gronk-less Patriots in Week 15, the Broncos would be 10-4 and in great shape to make it back to the postseason.

It also benefits the two favorites in the NFC, Dallas and Seattle, who combine to have a 65.3 percent chance of making it to the Super Bowl from the other side of the bracket. Both would rather not see Gronk. Among the their pass defenses, tight end coverage has been both teams' biggest issue. The Seahawks are 18th in defensive DVOA against tight ends, their worst mark against any position. It's even more noticeable for the Cowboys, who were the third-worst team in the league against tight ends heading into Thursday night's win over the Vikings. They will still have to deal with Bennett, but Gronkowski is unlikely to be marching on them in Houston.

What's next for Gronk?

This is the thorniest question of them all, and the one that is toughest to answer. Gronkowski has made critical decisions in his professional career with his back in mind. In 2009, Gronkowski missed his junior season at Arizona and underwent his first back surgery. He subsequently decided to go pro instead of returning to school to rebuild his stock, which almost never happens. Organizations passed on Gronkowski out of concerns about his back and the missing year of tape, which is how a Hall of Fame tight end gets taken 17 picks after Tim Tebow and falls to the Patriots in the second round.

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).

By getting that $8 million signing bonus two years before free agency, Gronkowski capped his future earnings over the next six years. With base salaries of less than $5 million between 2012 and 2017, the significant money in Gronkowski's deal came way down the line and was totally unguaranteed. (This is why you shouldn't listen when articles say somebody has the "biggest" contract unless it's talking about guaranteed money.) The first gate Gronkowski had to crash was 2016. The Patriots started footing the cap bill for a $10 million option bonus in 2015 but then actually paid the cash out to Gronk this year, stretching the other four cap hits for that bonus through each of the four remaining seasons on his deal.

Gronkowski will remain underpaid in 2017; he will have a cap hit of just $7 million, eighth among tight ends and below that of Dennis Pitta and Charles Clay. The money in his deal really only spikes for the first time in 2018, six years after his extension was signed, when Gronk's base salary rises from $4.25 million to $8 million and his cap hit jumps from $7 million to $11 million. In 2019, the final year of his deal, Gronkowski has a $9 million base salary and a $12 million cap hit.

Rob Gronkowski is believed to have suffered his initial chest injury on this hit from Earl Thomas. Adam Glanzman/Getty Images

The problem for Gronkowski is that none of that money is guaranteed. Zero. 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.

Gronkowski has dealt with a fractured forearm, infections in that arm and a torn ACL during his pro career, but his back has always loomed as the long-term problem. Gronkowski underwent his second "minor, preventative" back surgery in June 2013 amid reports that he would be back in time for Week 1. He didn't return until Week 7, a little more than four months after the surgery. Gronkowski had 114 yards against the Jets in his return, but seven weeks later, the torn ACL ended his season. He wasn't his old self until Week 5 of the following year, the famous "We're on to Cincinnati" blowout win over the Bengals that started New England's run to their most recent Super Bowl victory.

It's impossible to predict the timetable for Gronkowski's recovery or whether he'll be able to return to his previous level of play. What we can note, though, is that building an offense through tight ends is a tough way to make a living. Before the 2012 season, I conducted research on Gronkowski and Jimmy Graham, noting how tight ends were more susceptible to injury and had shorter careers than similarly gifted wide receivers.

This time around, there's also not much the Patriots can do to make it easier on their star receiver. Coach Bill Belichick already has made positive changes designed to ease the workload on Gronkowski. After Gronk famously fractured his forearm blocking on an extra point attempt, the Patriots took him off of special-teams duties. In an attempt to keep him healthy for the regular season, the Patriots have stopped using Gronkowski in the preseason; he hasn't taken a single preseason snap since the 2012 campaign. I've seen both articles and fans suggest that the Patriots hold Gronkowski out of meaningless regular-season games, but that's going to make him far less valuable, and it's not going to insulate him from injury. Remember: He suffered a chest injury against the Seahawks on a hit by Earl Thomas, as there were concerns Gronkowski might have punctured a lung on the play.

There also should not be any arguments calling for Gronkowski to change his style of play, as if shrinking from contact or avoiding full exertion would somehow fix his injury issues. The forearm injury was a fluke accident. He suffered the back strain that led to his college surgery in practice. As far as we know, he suffered his back injury against the Jets diving for an overthrown pass. The torn ACL he suffered was on contact, but it was a pass up the seam where he couldn't protect himself and Ward took out his knees. It's not as if he injured himself, say, throwing Sergio Brown out of the club.

The reality is that the Patriots and Gronkowski alike have known all along that injuries were going to be a part of the Gronk experience. It's how they ended up together in the first place; it has underpinned their contract negotiations; and it's an inescapable part of Gronkowski's future with the team. There's no way to eliminate it outside of keeping Gronk on the sidelines when he's healthy, which does nobody any good.