Yeah, it's a post about frames per second, but it's going in a different direction than usual. The standard is that a game runs at less than 60 FPS, and a lot of people get angry about it. This is about a title running at a much higher rate.
During a panel at Evo 2015 this past weekend, developers from Iron Galaxy said that Killer Instinct: Season 2 is running closer to 90 FPS. The game then rolls that back so the actual output on-screen is at 60 FPS. That's why the netplay is so smooth; everything's stable because the game isn't struggling to hit the 60 FPS benchmark, but instead it's operating about 50 percent above that.
Killer Instinct is actually a title that's often praised for its smooth performance on Xbox One to the degree that it sticks out from other games. It'll soon be available for cross-play between PCs running Windows 10 and Xbox One. Assuming there aren't optimization issues on PC, performance should be top-tier across both versions.
The FPS discussion can be found around the 43:15 mark of the embedded video.