WWE SummerSlam 2016: Most Exciting Swerves in Event's History

History says that fans should expect Sunday's WWE SummerSlam 2016 to feature one major surprise, one moment where the company tosses a swooping curveball into the stories unfolding in the squared circle.

The pay-per-view has become known for just that. As David Shoemaker wrote for Grantland, "SummerSlam has been a platform for big swerves in recent years, providing unexpected finishes to big matches."

SummerSlam's early history featured its fair share of the unexpected and eye-opening, but WWE has really relied on that narrative element of late. As a result, four of the top seven moments on this list happened in 2009 or later.

A sister's betrayal, an errant chair shot and Randy Orton's history-changing ambush are among SummerSlam's most startling moments. They are ranked on how surprising they were, how effectively WWE issued that surprise and how much they impacted the Superstars' involved from that point on.

What will Brock Lesnar, Finn Balor or Sasha Banks do at the latest edition of the event to add their names to the list? After consecutive years of SummerSlam swerves, fans now know that something out of left field is coming to The Biggest Party of the Summer.  

Honorable Mention: Jon Stewart Swings a Chair (2015)

If you saw Jon Stewart clocking John Cena with a chair coming, you might want to start your own psychic hotline.

The former host of The Daily Show was supposed to be the host of SummerSlam 2015, not a key factor in who came away with the WWE World Heavyweight and United States Championships. And considering all of Stewart's previous run-ins with Seth Rollins, one would expect that the comedian would attack the heel.

Stewart instead prevented Cena from winning the world title to make sure he didn't match Ric Flair's record for reigns with that belt. He attacked the powerhouse with a steel chair, and Rollins pounced to take advantage.

The surprise factor was off the charts here, but this was a reminder that the unexpected is not necessarily effective. 

The lack of explanation for Stewart's actions hurt the moment. He was out of place. The moment was absurdly random.

And it didn't help that Stewart's involvement overshadowed Rollins' major accomplishment. It wasn't the wrestler everyone was talking about after the show, but rather a TV personality who would soon be gone from the WWE world.

7. Undertaker Attacks CM Punk (2009)

File this under the same out-of-the-blue category as Jon Stewart's attack on John Cena. It was wholly unexpected that Undertaker would emerge from the darkness to dig his claws into CM Punk.

But where Stewart's amble down the entrance ramp and into the ring felt off balance, The Deadman's arrival was right at home in the nutty world of wrestling. One could easily assume that Undertaker was after Punk's gold.

WWE did well to creatively insert Undertaker, creating a lasting image in the process.

Just after Punk outlasted Jeff Hardy to win the World Heavyweight Championship, Undertaker appeared where Hardy was lying. Jason Powell of ProWrestling.net wrote, "Most of the fans didn't pick up on the fact that Taker was lying under Punk until he reached up and grabbed him by the throat. Very well done."

As cool a moment as that was, though, it didn't have the oomph that others higher on the list did. Undertaker forced us to drop our jaws. Other SummerSlam swerves made them drop even lower. 

6. Daniel Bryan Joins Team WWE (2010)

To combat the destructive crew of rookies that was The Nexus, John Cena formed a supergroup that included Edge, Bret Hart and Chris Jericho.

Cena waited until just before the match to reveal that the previously fired Daniel Bryan was Team WWE's seventh member.

WWE fans had last seen Bryan as a member of Nexus before receiving his walking papers. The company reinserted him into the roster in dramatic fashion, and the underdog stomped past old mentor The Miz en route to taking on his old stablemates.

Bryan hadn't yet developed a strong relationship with much of the audience, though. Shawn Valentino wrote for PWTorch in his review of the event, "Most mainstream fans are not too familiar with him."

That lessened the power of the surprise. Sure, it was unexpected to see him back, but it didn't mean nearly what it would have if the event had unfolded years later.

5. Nikki Bella Turns on Her Sister (2014)

Siblings have collided throughout WWE history, but many assumed that Nikki and Brie Bella would avoid that fate. They are twins, after all.

That didn't matter in the summer of 2014. Nikki showed up during her sister's big fight against Stephanie McMahon and seemed poised to help Brie. She instead floored her own flesh and blood, allowing the tyrannical McMahon to score a cheap win.

One didn't know what to make of it in the moment. Nikki's expression revealed her to be regretful and angry, but the audience would have to wait until after SummerSlam to discover what her motivation was.

The surprise factor was huge here. The Bella Twins had been inseparable before this. 

This was an exclamation point on a match that needed it.

Had this led to something other than a disappointing rivalry, fans would look back on it more fondly. SummerSlam's very best swerves were precursors to major happenings, shocks leading to memorable stories. 

4. Shawn Michaels Costs Undertaker the World Title (1997)

Shawn Michaels wearing referee stripes for the Bret Hart-Undertaker WWE title match at SummerSlam 1997 was sure to cause trouble. The audience just expected it to be directed elsewhere.

Michaels had ample animosity toward The Hitman. The predictable result would have been Michaels clocking his rival to cost him the match. Instead, he swung a chair at Hart and hit The Deadman. 

With the champion down, Michaels then had to count to three and award Hart the championship.

This bit of misdirection played with fans' expectations. It made sure to use Michaels' presence, end the title contest in surprising fashion and set up stories for the future. The simplest swerve is sometimes the best.

An enraged Undertaker would then hunt down Michaels, resulting in a number of classic matches including the inaugural Hell in a Cell bout.

3. Ultimate Warrior Answers Open Challenge (1988)

At the first edition of SummerSlam, fans thought they were about to see yet another match where The Honky Tonk Man found an underhanded way to retain the Intercontinental Championship. He was set to face Brutus Beefcake, but the announcers informed everyone that the challenger was unable to compete.

The champ then called out anyone in the locker room to take him on.

In charged The Ultimate Warrior, an emerging star surging with adrenaline. The surprise opponent then delivered a surprise result—the end of The Honky Tonk Man's record title reign in mere seconds.

This will remain one of the more fun SummerSlam swerves ever, but the event's two best swerves delivered resonating emotion along with surprise. 

2. Paul Bearer Turns on Undertaker (1996)

More than the usual wrestler-manager pairing, Paul Bearer and Undertaker were deeply connected, each character integral to the other.

Bearer carried around The Deadman's urn, the object said to contain the source of his power. For five years, he had been Undertaker's mouthpiece and constant ally.

All that ended (albeit temporarily) in 1996.

Undertaker and Mankind moved their fight to the ring after battling inside the boiler room. Bearer soon smashed his own client with the urn, signaling a shift in allegiance to Mankind.

This remains one of the most shocking betrayals WWE has showcased, at SummerSlam or elsewhere.

The argument for whether this should then be SummerSlam's best swerve depends on one's philosophy about the art of that narrative element. Randy Orton's Money in the Bank cash-in offered more hints of what was to come, using foreshadowing to amplify the moment. This was more of the from-out-of-nowhere variety.

WWE tore an alliance apart in sudden, surprising fashion here. Orton's insertion into the 2013 SummerSlam main event resulted in something more powerful. 

1. Randy Orton Cashes In on Daniel Bryan (2013)

Randy Orton preying on Daniel Bryan after his huge win over John Cena for the WWE World Heavyweight Championship was a prime example of the power of planting narrative seeds.

Orton had warned Bryan that he would be looming with his Money in the Bank contract in hand. Special guest referee Triple H had expressed reservations about what a Bryan championship reign would look like.

While more fans saw this coming than Nikki Bella's turn or Paul Bearer's betrayal of The Undertaker, it was the most electric of all those moments. 

WWE handed us the happy ending fans wanted, as the underdog made it to the mountaintop. But as Bryan celebrated and the confetti fell, the company broke our hearts. Evil prevailed. The world was upended.

Cageside Seats' Geno Mrosko wrote of the emotions of the moment, "I'm supposed to feel like this, if I'm worth my salt as a fan. That's why this was such a victory for WWE."

In addition, this was the catalyst for the creation of The Authority, a group that dominated storylines for years afterward. This was the first chapter in Bryan's moving story that culminated at WrestleMania XXX. In retrospect, that adds to the weight of that first painful stumble courtesy of Triple H and The Viper.

WWE will likely offer fans a new swerve during SummerSlam 2016, but the company will be hard-pressed to top the best surprises the event has delivered up to this point.