#2 To push McIntyre to the moon
This might sound crazy, but just because Drew McIntyre is facing Roman Reigns, it doesn't necessarily mean that Reigns is going to win. Sure, the odds are certainly going to favour Reigns, and it being WWE, they probably want Reigns to get a big comeback win.
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But perhaps there's potential to do something much bigger and better. If McIntyre faces and displaces the top star of the company (and clean at that), it'll give him a lot of momentum going forward.
Post-WrestleMania is an extremely exciting time, and giving McIntyre the big win most certainly means that he's getting a big push going forward.
It'll also fit well with the narrative that he tore down The Shield. With only one member left to slay, it could turn out to be a career-defining moment for The Scottish Psychopath.
The good thing is that despite having less momentum, he's been well protected.