In 2012, the Republican presidential primary was an afterthought, occurring after the contest was secured, and with an overwhelmingly victory for favorite son Mitt Romney. This cycle, Utah voted at a more pivotal moment.
Donald Trump has been running very well in some areas (although still having trouble getting a majority in any state), and not so well in others. One of his weaker areas in the contests so far has been in western and great plains states. Perhaps, the pundits have said, the New York mannerisms of the bigmouthed Trump, do not sit well with the conservative, polite people of the American heartland. This was thought to be especially the case in Utah, where the Mormon population that makes up the majority of the Republican electorate was thought to be especially averse to Trump's brand of politics.
While the "why" is still up in the air, the results of the race were rather dramatic: Ted Cruz won with 69 percent of the vote, against 17 percent for John Kasich and a small 14 percent for Trump. It wasn't clear whether people were voting for Cruz (who has problems of his own) or against Trump. It could be seen as a bad sign for Trump, but there aren't a lot of states like Utah left to vote: Colorado, Montana, the Dakotas and Nebraska can still give their delegates to Cruz, but compared to the big prizes of New York and California, these states aren't that rich in delegates. So, while Trump still has groups of the Republican Party who are averse to him, it isn't clear that they will be able to stop his nomination.