#2. They close the show
A match like Roman Reigns vs. The Rock surely would have main evented WrestleMania 35 for the combination of Rock’s overwhelming star power and WWE pushing Reigns as the top star of today. The Rock vs. Shawn Michaels is a bit less certain proposition to close out the biggest show of the year, given that both men are part-timers at best, wouldn’t have a title at stake, and there would be some questions regarding their quality of performance given the degree of ring rust between them.
However, it’s tough for anything to follow Rock’s electricity when he steps into a WWE ring, and Michaels built a legacy on turning in genuinely great matches in the highest profile contexts possible. For sheer star power, as well as the match’s potential to steal the show, it’s hard to imagine any match main eventing over The Great One vs. The Showstopper.