In Monday's Iowa caucus, Senator Ted Cruz, R-Texas, the man most hated by the Republican establishment, came from behind to nab front-runner Donald Trump. Senator Marco Rubio, R-Fla., the supposed establishment favorite, came in just a point behind Trump. According to conventional wisdom, this should set up a battle royal among anti-establishment Cruz, anti-establishment Trump and establishment Rubio. If Rubio emerges victorious, the pundits explain, the establishment will have lived to fight another day, and put those rowdy conservative grass-roots anti-establishment types in their place. This is nonsense. Cruz is the most conservative person in the Republican race. Trump, up...