These results have been bouncing around a bit without any apparently explanation, I presume the methodology is variable with time and I don't take the exact numbers too seriously.
That said, this is the best time in history to be a Linux gamer. If you have AMD graphics then your system probably works great. If you have Nvidia, results will probably vary a whole lot, but at least features will work. (Only old school SLI is really missing.) Proton is very stable and recently there have been some nice improvements in areas like load time and menu responsiveness. From my informal testing, it seems like some of that is NTSYNC.
And it's also the worst time in history to be a Windows user, if only because you could still get Windows 98SE when Windows ME had come out...