I actually enjoy Rove’s analysis, but you have to take it with a grain of salt. He does have his own agenda and was Bush’s top election adviser. We will see if Trump has a ceiling. It is not surprising to me that he slightly underperformed some of the polls... What was spent on negative ads in SC in the weeks before the primary? Does he think that tens of millions of dollars of negative ads directed at Trump would have no effect.
Support for candidates does tend to be cyclic over a number of months. However I think that it is more likely that Trumps popularity will continue to rise and Rove will have egg on his face.
Trump unperformed 2 out of 15 SC polls. Hardly anything to get excited about if you are an honest, as opposed to a Rove style, political analysis