I would have to respectfully disagree. Billy Gunn has a few gimmicks over the years before teaming with the Road Dogg, that went nowhere, and relegated him to an opening act. When Gunn was with DX, he was great with the New Age Outlaws, but the problem was that the Road Dogg had all the charisma in the group, and this helped hide Gunn's limited ability to work the mike. He had the look, but his wrestling skills were never great, and once he left DX, he never really got over with the fans.Interesting question. WWE has tried with a fair few guys and failed. Billy Gunn is a pretty good example of a great midcard/upper midcard act that they tried to push into the main event scene but it didn't work out. With Gunn it's odd as well because in reality he has all the tools that WWE main event guys have. He was solid at the very least on the mic, had a big body and was a good looking dude, had charisma, was a solid enough wrestler. It just didn't resonate with the audience for whatever reason.
Sid's lack of main event success had more to do with his work ethic, He had the look, and the charisma to be a top guy. Unfortunately he was stiff in the ring. This is a guy who got cheers for beating Hulk Hogan in the Royal Rumble, and Shawn Michaels in late 1996. He also had backstage issues with many, that did nothing for his career.If other promotions count I'd point to WCW and say that Sid Vicious in 99-01 seemed really out of place as a top main event talent and the well publicized push of Chris Benoit wasn't working either. WCW tried to make stars out of Billy Kidman, David Flair, Mike Awesome and Vampiro as well heavily pushing them in 2000 but none of them really caught on at all and were pretty bad choices for the future crop of main event WCW stars.
Benoit could ahve worked as a main event draw, but the problems are the WCW never built him up properly before winning the title. In the previous months, he had lost to Bret Hart, and was on the losing end of some matches with Jeff Jarrett. They needed him to go over Hart, and possibly either Nash and Hall, before beating Sid for the belt, and make him credible.
Mike Awesome is another guy they dropped the ball with. A monster of a man, with a hard work ethnic at his peak, should have had feuds with guys like Nash, Steiner, and Goldberg. Instead they stuck him with lame gimmicks. Kidman, Daivd Flair, and Vampiro never caught on with fans, and top starts.