To my eye the Epic has far and away the nicest image. The Epic was focused on the foreground tree, so when the blew up the out of focus region - surprise, surprise it looks out of focus.
The 5D blow up looks like it was the victim of a combination of an out of focus image and scaling issues.
Remember they're using an 80-200, and the Epic and 5D have much bigger sensors than the GH4. So if the Epic and 5D were sitting around 160mm to get that shot size, it's likely that they needed to have the GH4 at around 80mm to match, which would explain the reason there's more apparent sharpness - as more of the image is in focus. Of course, they easily could have focused the GH4 one the roof, and the other two on the tree just to rig it, but it almost looks like they gave absolutely no thought to focus at all.