Ok. Top 15 what? Online FPS games? Your link shows me statistics, but without comparison, they don't mean a lot.
I am not trying to be argumentative at all, but "in the top 15" in this particular genre isn't what I would call especially 'popular', particularly seeing as it is a recent release; one would think it might be higher, at least initially. Also, technically it is a third-person shooter, but that might be being pedantic.
I wasn't trying to bash any game, but just to make a point. Perhaps Warframe was best left out of my mix, but I don't see it being a particularly 'splashy' release. Again, not that it is a bad game, but I think the arena shooter is seen as passe these days, which is why these new entries into the genre will not become 'the next UT'. UT4 will do well thanks to its roots being 'back in the day', one of the founding members of the club, as it were. In a genre like FPSs, heritage/lineage means a lot and all of the others are always viewed comparatively. That Warframe was developed by DE, who had a hand in the UT series, gives it some credibility, but nonetheless, it is still seen through UT glasses.