Rubio isn't a bad candidate even though I would have supported Crist. It's not a surprise that he's pulling away as Crist isn't as popular as he needs to be to be able to win as an independent. I expect Rubio to win comfortably.
Rubio is an incredibly talented candidate. He evokes controlled, reasoned passion, and is very articulate. Of all the insurgent primary winners, he is in a class by himself really. It is too bad that I think he may be ethically challenged. Such is life.
Crist has closer connections to Jim Greer who was actually arrested.
Hopefully Floridians are realizing that Crist is an establishment hack who had the support of the elites of the FL GOP including as you mentioned, connections to Greer over Rubio in the primary.