[Bruce Campbells Chin]

I think Rubio did better than predicted because many of the fence-sitters were the "GOP-E", and were undecided as to which of the establishment candidates to support.

Coming down the homestretch, Rubio was in the lead among the non-Trump/Cruz voters. Then he had a strong debate, and so a lot of the undecideds and even supporters of other establishment candidates broke his way late when they saw he had the best chance.

That seems pretty logical to me, although the only actual evidence I have to support that is the entry polls showing that Rubio did very well among late deciding voters.

[Rational Thought]

Let’s just assume that’s the reason for now...meaning the establishment candidates are far from done.