Seems to me that there's only one ball, so outnumbering the ball must mean double (or more) teaming the man with the ball, and moving the double team when he gives up possession. If he means anything else by it, only Seth would know.
I think "outnumbering the ball" (granted, I've never heard this term before so this is an educated guess) means loading up the strong side defensively. If the ball is on the right wing, for instance, then KO would want probably four defenders on that side of the court and at least four pairs of eyes on the ball. Their appears to be a growing emphasis among coaches on restricting corner three opportunities and forcing the ball to areas of the floor that are less conducive to high percentage shots. It seems to be a philosophy many of the great defensive teams in the NBA like Chicago and San Antonio have adopted in recent years - the goal is to stack the defense with as many layers of help as possible as a way of limiting p&r opportunities. The thinking is that, - and at the college level where offense is less crisp, this may be especially true - the more passes you force an offense into making (especially from side to side, passes that are notoriously more likely to be intercepted), the smaller their margin of error.
It' something I noticed this summer when I was watching tape from last season. UConn rarely doubled the ball, but on post ups, both of the guard would generally sag into the paint to force the opposing big man into split-second decisions. The general idea is to restrict dribble penetration and post ups and capitalize on the underbelly of most college half court offenses (which is ball movement). I get the feeling schemes like this really provide insight into KO's NBA background. We're very fortunate to have him, because I don't think many coaches get this innovative with their defensive sets.