Re: Aikido does not work at all in a fight.
Aikido may work in a street fight, but it is not based around street fighting. MMA works well in a street fight because it is very much based around the tactics used in common street fights (striking and grappling). Krav Maga works great in a street fight, because it is designed specifically for that purpose.
That being said, a skilled aikidoist would already know the limitation of his martial art, so he would likely know the appropriate course of action to take in a street fight in order to give himself an advantage. Perhaps engaging his adversary in a conventional way, then looking for opportunities to apply locks, levers, and throws when the moment is right.
And just to make sure I have used the apparent minimum quota of the word "aiki" in my post....aiki aiki aiki aiki aiki aiki aiki aiki aiki aiki.