All that means is the people who were sitting on the ask got impatient and decided to sell their shares at the bid.
Therefore, the ask got lighter (because those sellers are no longer trying to sell at the ask) after the bidwhacks...
Not an MM game in the slightest....
For example... Person A has 500k of shares sitting at the ask.... he/she gets worried that no one will be slapping the ask, so Person A decides to 'play it safe' and lock in profits by bidwhacking... so there is a bidwhack to Person B (who is sitting on the bid)...
Well, now there are no longer 500k worth of shares sitting on the ask, therefore the ask becomes lighter, or in some cases will increase after the bidwhack...