Miz isn't even a credible main event star in his own field.
He can talk his ass off, but his entire presentation is mid card- which is where he's been. He's great at being a mid card pro wrestler with a mid card gimmick, who just so happens to have main event speaking ability.
He's smug, arrogant, etc, but despite the wwe and reality tv fans (and Boone, apparently) trying to make this a thing, Miz isn't Johnny Cage.
All this is apart from the fact that he's shown nothing even resembling martial arts skills.
Can he throw a believable sidekick? The splits? Cause that shit will be needed.
Ryan Reynolds would make that shit pop though, because he's got pretty much everything needed, both for the character and the movie, because this shit desperately needs a star. RR isn't exactly the greatest, but he's fantastic in certain situations, and I think Cage is a perfect fit.
We'll probably get some generic CW type actor for this shit though.