Marco Rubio has been hammered pretty hard since Saturday night about sounding "too robotic" to be a viable candidate. The basis for this accusation was his repetition of the idea that Barack Obama isn't someone ignorant of what he's doing to the country. He is maliciously doing exactly what he planned to do all along. He was called out on this by Chris Christie in the fateful exchange that has many in the media believing it is the end of Marcomentum as we know it.
However, what Rubio was doing is something that is a very basic rhetorical skill taught to seventh graders (I know this because I teach this to seventh graders). You see, in argumentative and persuasive communication, a common tactic is repetition. This tactic is called a "rhetorical device," along with two others that are taught to seventh graders: parallel structure and rhetorical questioning.
Rubio's only fault here is that he did it too obviously. Does it mean he's unprepared for the role of president? Not at all. In fact, Christie was guilty of using basic rhetorical devices as well.
Parallel structure is basically listing things in such a way that they all appear equal or simultaneous. In his exchange with Rubio, Christie lists off the things executives are expected to do, stating "See, Marco, when you're president of the United States, when you're governor of a state..." and goes on as if the two jobs are equal. He then says of constituents that "they expect you to plow the snow, they expect you to get the schools open, and when the worst natural disaster in your state's history hits you, they expect you to rebuild your state," placing all of those tasks on the same level and hinting that they are on a level above what a first term senator can do.
He also asks Rubio rhetorically if a newly-elected senator gets extra-sensory perception when he is elected. A rhetorical question is another rhetorical device used when you ask a question that really isn't supposed to get an answer. They often take on a sarcastic tone, as well.
Neither Christie's parallel structure nor his rhetorical question actually add anything to the debate or the race in general. Plowing snow and opening schools are no more the job of a president than being commander in chief of the United States armed forces is the job of a governor. Asking sarcastically if Rubio has ESP doesn't make Christie better than Rubio.
The sin Rubio is guilty of is not knowing how to engage someone like Chris Christie, and that is knowledge he will need going forward. He is still debating as a Senator, and not as a presidential candidate. That does not make him any less qualified to be president. It just means he needs to prepare himself to take on Hillary (or Bernie???) should he be the ultimate winner in the Republican race for the nomination.