Donald Trump's timing in the 2016 presidential campaign has been impeccable. He got into the race just as dissatisfaction with the crop of candidates was rising. He began peaking as fall turned to winter, right in time for a series of critical votes nationwide. He has been in the right place at the right time almost every time. Until this week. After taking last week off the campaign trail -- totally unheard of for a candidate in the midst of a contested primary fight -- Trump needed this week to be a momentum-builder before Tuesday's winner-take-most Wisconsin primary. It has been the exact opposite.