#4 WWE generally doesn't book heel vs. heel main events
Elaborating on WWE's habit of booking major title changes before Survivor Series, a couple of them were due to improper alignments between RAW's and SmackDown's Champions. Some of the beneficiaries of this were AJ Styles and Charlotte Flair, who faced Brock Lesnar and Alexa Bliss, respectively, at Survivor Series 2017.
While there are a few exceptions, notably at Survivor Series itself, WWE is generally against pitting two bad guys opposite each other. There is nobody the fans could root for in this scenario. It takes two exceptional talents to make such a match work.
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Roman Reigns and Randy Orton are both exceptional storytellers and would undoubtedly work around the constraints of their alignments. They would bypass this problem, much like Brock Lesnar and Daniel Bryan did two years ago. That match was a genuine classic.
That being said, WWE would still likely prefer a babyface to step up to the Tribal Chief, which is why Drew McIntyre has a fighting chance on RAW. The dynamic would be much better between him and Reigns than it would be between Orton and Reigns.
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