We know who the top three are, though we don’t yet know what order they will finish in. But we do know for certain that some former Iowa frontrunners now have the same chance of winning the caucuses as Jon Huntsman, Buddy Roemer, Herman Cain, and Fred Karger: zero. Let’s examine what happened to each of them.

Newt Gingrich: Like the other not-Romneys before him, Gingrich couldn’t withstand the sustained scrutiny of his record and temperament. Gingrich led House Republicans to the promised land in the 1990s and his majority produced some solid conservative policy accomplishments from 1995-97. But he always had a side to him that was undermining his own cause, whether it was pushing himself to the left of the more committed spending-cutters in his caucus or simply coating his message with arrogance. That history came back to haunt him and there were enough new manifestations of these character traits to make the anti-Gingrich ads sound plausible to Republican ears.

Rick Perry: Perry seemed to briefly square the circle for Republicans who wanted a nominee who was more conservative than Mitt Romney but could still beat Barack Obama. He was the governor of a large state with a record of job creation that contrasted nicely with Obama’s. But in his disastrous debate performances, Perry quickly cast doubt on his two strongest assets: his conservatism and his electability. Voters began to suspect he wasn’t as conservative as advertised and that his sub-Bush speaking skills, among other problems, would get him clobbered in the general. Recent reporting suggests his campaign team was divided between Texans who thought running for president would be no different than running for governor and outsiders whose anonymous quotes to news outlets like Politico raise questions about how invested they were in the outcome.

Michele Bachmann: What caused Bachmann to crash from winning the Ames straw poll — and leading scientific polls of Iowans — to last place among the major candidates actively contesting the caucuses? My sense is that she had three problems: Perry jumped into the race at her moment of triumph, stealing the spotlight and many of her still-fluid supporters; she spent a lot of money to win Ames and wasn’t immediately able to fight for the support she was losing to Perry; Republicans were initially attracted to her because she was one of them but ended up wanting a little bit more out of a future president.

It remains to be seen what these three candidates will do in the aftermath.