Trump also happened to win the debate by not showing up. Now this was not a foregone conclusion, but the result of the weakness of his opposition. The debate could have been an opportunity for the candidates to prove, in Trump's absence, that the Republican party is a highly functioning organization with ideas to offer to solve the nation's problems. Instead, it exposed a party gone off the rails, dysfunctional and playing the lowest common denominator of its base. No single candidate was able to use the debate to elevate himself to the position of the anti-Trump as a result.
The more I think about it, the crazier this situation seems to me. I have to strain my brain, but I can remember a time when the Republican Party was a much different beast. I put the cut-off around the time of the 1994 takeover of Congress by Newt Gingrich. Before that time, the notion that Republicans would try to shut down the government to get what they want or to impeach the president over issues in his personal life would've been ridiculous. Republicans held to policies that I did not agree with, but they appeared to be serious people who I at least had to listen to. On that stage Bush and Kasich, who were on the conservative end of the party in the 90s, were the only candidates to fit into this category. They also happen to lag far behind in the polls. Bush especially seems like a relic of a bygone time. At least in this debate he sounded like he had some fire in his belly.
The other candidates simply cannot be taken seriously by anyone who is not already a conservative Republican. Carson and Cruz are just flat-out non-starters. Paul's libertarianism (he would not have voted for the Civil Rights Act) also puts him on the fringe. Christie actually had the chutzpah to go after Clinton's emails while an indictment involving hidden emails is hanging over his own head. Rubio once looked like the great establishment hope, but he comes across as a total lightweight, searching for ways to work in his slogans whenever he can. On top of that, despite his youth, his political positions are actually very far right, especially in foreign policy. For the most part these candidates doled out red meat to the baying hounds of the conservative base. It is nearly impossible for me to imagine any of them as leaders of such a diverse and multifaceted nation such as ours.
In a way, this the consequence of a strategy that has been very successful for Republicans in other areas. They have been ginning up the outrage of their base from the day that Barack Obama took office, and have used that outrage to win lightly attended midterm elections and to get ideologues in charge of Republican-heavy states. The result has been a Congress unwilling to compromise, and the likes of Brownback, Walker, and Snyder shredding the social contracts of their states. They can dominate local elections with low turnout, but when it comes to the one national election (for president), that same base frightens off the middle-of-the-road voters who only come out every four years. This causes much angst with the base, who often blame the losses by McCain and Romney on the fact that they were not conservative enough.
The result is a dysfunctional party that is very good at throwing up roadblocks and winning local elections, but is tearing itself apart. Trump's presence has exposed all of this. A large number of conservative voters want more than dog whistles on immigration, and Trump gives them full on hatred. While they want to deny welfare to "those people" those same voters want a social safety net for themselves, and thus aren't really behind the Koch-ist libertarianism popular in much of the party's establishment. Trump, who has pledged to fund Social Security and Medicare, seems to understand this, too. They want military victory but without any long-term occupations, and Trump too promises such a magical outcome. The GOP has benefited from having an engaged base of supporters, but now appear unable to control them, or to get them to keep voting for candidates who don't really want to give them what they want. Trump, unlike other pretenders to the conservative crown, has the independence, force of personality, and fame to actually unify that base. Don't be surprised if the establishment doesn't decide to throw their lot in with him, if only to save their own skins by going with the base of their party. These are strange and scary times indeed.