#4 Mishandling world-class talent
WCW took great pains to collect some of the biggest stars in wrestling. Hulk Hogan, Roddy Piper, Macho Man Randy Savage, Bret Hart and others were all on the roster at the same time.
However, egos and other conflicts led to a gross misuse of these legendary men. For example, Bischoff didn't think Hogan vs. Bret Hart would be a draw (and neither did Hogan according to some rumors) so the two never had a definitive feud. Sting and Lex Luger, once the biggest stars of WCW, were relegated to the tag team division until Sting started his 'crow' gimmick. And Scott Hall and Kevin Nash–certified main eventers in WWE–were just glorified sidekicks to Hulk Hogan in the nWo.
Not using the world caliber talent at their disposal was one of the mistakes that led WCW to ruin.