It's a weird perspective to be looking at them, as we fans don't have a view from below of fights, so that's the first thing that makes it weird. It's framed like we're lying on our backs looking up at them looking at each other.
I guess whoever made it was going for a Kubrick/The Shining kind of effect (where Jack is talking to Wendy through the door and we're looking straight up at Jack) but it just looks very strange in this context. You don't want to see an upside down fighter on a PPV poster.
And the poster is bottom-heavy, with Jones taking up much more real estate than Cormier.