One of two things happened in Louisiana. We know that the margins between the top three candidates in the state shifted dramatically between votes cast by absentee ballot and those cast on Saturday, the day of the election. That means that either that: 1) A candidate had a very strong get-out-the-vote effort, or 2) There was a broad shift in attitudes about the candidates.
When we looked at this Saturday night, it wasn't clear which was the case. Now, we have a better sense.
If we look at the votes in counties* for which we have data (culled from the AP's initial and final vote tallies), you can see that Ted Cruz gained strength after the absentee vote. The darker the county, the higher the vote percentage. Cruz's map gets darker. Donald Trump and Marco Rubio's get lighter -- the latter, dramatically so.
Another way of looking at it is the percentage-point shift between the final percentage in each county and the percentage from the early totals. Cruz's map is all blue, all increased. Rubio's is not.
One more way of looking at it, showing the shifts more clearly still. Anything above the line means an improvement between the final or day-of percent and the absentee totals.
Widespread. This suggests that the shift probably wasn't a function of Ted Cruz's (clearly strong) get-out-the-vote effort. Field efforts like that result in relatively limited swings, and it's hard to see how they could have run a hugely successful turnout effort throughout the state uniformly.
Instead, this looks like the state of Louisiana bailed on Marco Rubio in favor of Ted Cruz. Which could explain why Cruz is targeting Florida all of a sudden. On Saturday night, Donald Trump called for Rubio to drop out of the race. If he can repeat what he did in Louisiana in Florida in just over a week, Cruz will take Rubio out himself.
* Yes, I know, they're called "parishes" in Louisiana. But unless Louisianans regularly refer to the "commonwealth of Massachusetts," I'll use a term with which people are more familiar.