Random change will eventually balance out in the long run, so I feel this is just like a lobo.
But what if the percentages for either a decrease or increase swung in favor of buff? (say, 30% chance to decrease; 70% chance to increase) Just throwing numbers out.
EDIT: Kinda ninja'd.
That'd be interesting. Make upped and unupped swing in different ways. It's a slight debuff or buff combined with lobo.