Some people seem to be a little confused at the resolution thinking that it upscales from 960x1080 to 1920x1080 like you would upscale a sub 1080p game to 1080p, it doesn't. I made some images to help.
Okay, so let's say the red lines are what is being updated while the black lines are empty space.
Now this is what it looks like on frame 1
On frame 2 this is what it looks like
And when frame 2 comes it it blurs the information from frame 1 to fill in the black spaces. This is why it looks fine when standing still but looks blurry and odd in motion. If we could take a single frame of KZSF's multiplayer with this effect turned off it would look something like this.
Zoom in to see the full effect.
The grey lines are dead space where nothing is being rendered on this frame.
So techinically the game is rendering at 1920x1080, just not on each frame.