This is the best video explanation I've found of what I've been teaching and calling the aiki brush-off. Just like this guy mentions in these videos, if you watch most aikido randori sessions, the tori is concentrating on applying techniques to each successive attacker. Problem is, this ties the tori up, creating openings for the other attackers. Most of the time, when you see really successful aiki randori practitioners, they brush-off more attacks than they counter with actual techniques.
This type of brushing-off action is what I've been concentrating on in my personal practice and in my teaching for the last couple of years and it has really changed my aiki for the better. I've had several highly-ranked folks whose opinions count a lot to me say that my aiki has become more robust and effective, while at the same time becoming softer. I attribute this to practicing the aiki brush-off.
Another interesting thing to note about these randori sessions: when the brush-off either fails or creates enough time to actually do a technique, the two techniques that pop up most often are shomenate and aigamaeate (A.K.A. aikinage or iriminage). Just exactly like the results we've gotten in knife randori like here and here. Atemiwaza is the first backup for the brushoff. Everything else in the art is backup for the atemiwaza.