#2 Rob Van Dam (Suffered in 2002)

Rob Van Dam's WWE career was filled with ups and downs. Every time he was about to get a big push, a setback ended up happening.
Van Dam made his WWE debut as a heel in 2001. He was a part of Team Alliance during the Invasion story-line. Due to his innovative in-ring style, Van Dam quickly won over the fans. He turned face immediately after the Invasion story-line ended.
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When the brand split happened in 2002, and the WWE Title became an exclusive property of the SmackDown Brand, Raw intended to introduce its own World Title (The World Heavyweight title of WCW). Rob Van Dam was supposed to be the inaugural Champion.
Sadly, that didn't end up happening and Triple H became the inaugural Champion. The original plan for Triple H was to be involved in a feud with nWo throughout the Summer.
However, Kevin Nash suffered an injury in June. After that, the entire nWo disbanded and all plans involving them were scrapped. Triple H ended up reforming DX with Shawn Michaels, only to turn heel on him.
Triple H quickly jumped up the card and ended up becoming the inaugural World Champion (in WWE).
Rob Van Dam, on the other hand, faded into the background slowly and became a mid-carder by the end of the year. Thus, Nash's injury led to Van Dam's push getting scrapped.