Huh?  Your analysis is faulty. You are trying to conflate two completely different things. Football and mixed martial arts are not  the arts in the accepted sense. The "arts" as referred to in mixed martial arts means technique (as in the "art" of war, cooking, basketweaving or other uses like that)  and is not the same as the fine and/or performing arts, which refer to fields of creative endeavour. 

It is not a denigration or mocking in any way but simply a pointing out of the obvious. But not obvious enough for some it seems.