Hmm, let's see...
Alberto Del Rio. Royal Rumble winner, MITB, four time World Champion/WWE Champion, two time US Champion... Since then he's burned bridges with WWE and TNA and is back in the indies.
Jinder Mahal. Went from zero to World Champion overnight and seemingly back to zero just as quick.
Jack Swagger. MITB, World Champion, cited to be the next big star - ended up with a "You don't know Jack!" gimmick as a white hipster of some kind before being released from WWE and doing essentially nothing since.

Thanks Taker_2004 for the banner!
Just been reading about Jack Rodwell signing for Blackburn, and boy has his career gone downhill fast! He joined Sunderland in 2014 having won the title twice, was an England International. He was then injured a lot, only payed 73 times in three years and never won a Premiership game since moving. Successive relegations with Sunderland and then had his contract torn up and has been looking for a new club for months before Blackburn have signed him on until the end of the season. It's really crazy how such a bright prospect and had everything looking up for him just turned to complete shit and can't get a decent job now. Defintiely not one as high as he was.
Why is this in the wrestling section with all this talk about football? Good question people, and the title should say it all. It got me thinking. Has there been any wrestlers that have had spectacular falls from grace like this?