#5 - Dolph Ziggler gets a concussion (2013)

For the last decade or so, Dolph Ziggler has been one of the more talented wrestlers on the roster. When he won the Money in the Bank Ladder Match in 2012, fans were elated to know that someone as deserving as Ziggler would eventually earn the company's top prize.
And eventually, he did - the night after WrestleMania 29, Ziggler successfully cashed in his briefcase on Alberto Del Rio, making him the new World Heavyweight Champion in one of the most genuine "feel good" pro-wrestling moments in recent memory.
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If you blinked, you missed his title reign.
A little over a month into his reign, Ziggler suffered a concussion during a match with Jack Swagger on SmackDown. He didn't have to relinquish the title, but he did have to miss his scheduled Triple Threat match between himself, Swagger, and Del Rio at that year's Extreme Rules PPV. He came back a month later, only to drop the title to Del Rio at Payback. Though he came close on a couple of occasions, he would never taste championship gold again.
Now, it seems as if WWE is making a concerted effort to ensure that no one ever sees Dolph Ziggler as a main-eventer ever again.