After seven years away, CM Punk has finally made his return to pro wrestling. He opened the second episode of AEW Rampage, to a massive ovation.Punk's appearance was as electric as expected. He was visibly emotional, before cutting an excellent and passionate promo. The Chicago-native is set to go on a career-defining run as the biggest star in Tony Khan's promotion.Fans have had an appetite for CM Punk to return to pro wrestling ever since he quit WWE in his prime. He was outspoken about his departure from the company, citing various instances that contributed to it. Some of them were from a creative standpoint.Perhaps more than most superstars, WWE constantly dropped the ball with him. He constantly proved himself as a star, but his booking would be a constant barrier. The Second City Saint would have become a WWE megastar, as he is set to be for AEW, but a few glaring errors truly stunted his growth.Let's take a look at the five biggest mistakes WWE made with CM Punk during his time there.#5 Ending CM Punk's first world title reign without losing a match (2008)9/7/2008Chris Jericho (replacing CM Punk) won the vacant World Heavyweight Title in a Scramble match at #Unforgiven from the Quicken Loans Arena in #WWECleveland, Ohio.#ChrisJericho #Y2J #CMPunk #Batista #JBL #Kane #ReyMysterio #BigGoldBelt #WWE #WWELegends #WWEHistory pic.twitter.com/jeVf9mJXt4— Instagram: AWrestlingHistorian (@LetsGoBackToWCW) September 7, 2020CM Punk's first shot at the top of the card in WWE came in 2008, following a couple of years as a part of the revamped ECW brand. He won the Money in the Bank Ladder Match at WrestleMania 24 and cashed in his contract on Edge to win the World Heavyweight Championship three months later.However, this reign wasn't very good. Punk barely defeated any top stars, with his biggest win coming against JBL at SummerSlam 2008. But the worst part about it was how it ended. WWE did not even let The Straight Edge Superstar drop his belt to another star.Punk was scheduled to defend the title in a scramble match at Unforgiven but was attacked backstage by Randy Orton. He was then replaced in the match by Chris Jericho, who won the big gold belt that night.Any momentum Punk garnered over his first world title reign was squandered when he was removed from his own title defense. Fortunately, WWE regrouped with the Chicago-native and his second Money in the Bank cash-in yielded more successful results.