#1 Rob Van Dam - 2006
Rob Van Dam was destined to be a big star in WWE. RVD hit WWE in 2001 to much fanfare. Initially debuting as a heel member of the Alliance, RVD was still so popular that he won the PWI Most Popular Superstar of The Year award for 2001, the only wrestler ever to do so while being a heel.
His popularity rewarded him with a main event push in October 2001. Although he lost his WWE Championship match, he remained the most popular Superstar in WWE, but his push eventually slowed down. By the beginning of 2002, he was just another Superstar lost in the shuffle. After competing in some of the best matches of 2002, Rob was given another shot at the main event scene, he briefly feuded with Triple H for the World Heavyweight Championship, but after falling to the Game at Unforgiven 2002, it seemed like WWE had once again lost interest in him as a main event player.
Yes, RVD's first 3 years with WWE were full of stops and false starts. After being out of action for all of 2005, RVD returned in 2006 to a prominent position, winning the Money in The Bank and WWE Championship from John Cena at ECW One Night Stand.
RVD lost his push just 3 weeks later, due to the aforementioned arrest of he and Sabu for possession of drug paraphernalia, and nine Vicodin tablets in his car. He returned to mostly a mid-card run until he left WWE in 2007.
Rob had a memorable main event run with TNA Wrestling from 2010 - 2013. He returned to WWE in 2013 and had a main event run, feuding with Alberto Del Rio for the World Heavyweight Championship, but went right down the card following his second return.
Regardless of WWE losing faith in him during his first couple of years, and his second WWE return and TNA run, it was unfortunately Rob Van Dam himself who ruined his major push in 2006.