In Tennis you have mixed doubles, but then you also have the womens and mens game too. Tennis is completely different to football though. If I was in a mens football team I wouldn't mind doing an exchange with you so I could play in an all womans team and you could join in the all mens. I think with football though if there was a professional mixed game separate from the mens and womens like there is with Tennis then you would need to have some sort of quota system so that you have at least 5 women in the team. If you had no quota system and it was on the basis of who was actually the best, then I'm afraid I don't think any women would get in at all escept for an extremely rare occurance of an exceptionaly gifted female footballer. Even if that woman was so gifted, still may not be quite at the standard of the worst man in the team. Perhaps there are some women who are really skillful at football I don't disagree with you, but would they also be highly rated in all other categories as well? E.g. Stamina, Strength, Arial ability, pace, tackling, zonal marking, offside rule etc etc. Being skillful alone doesn't cut the mustard you have to have a lot more.