Iowa caucus history
1980 Iowa picks George H.W. Bush, voting against Reagan. Against the Reagan Revolution. Against the hero to all Republicans.
1988 Despite picking Bush in 1980, this time they go with Dole. Bush wins the nomination with 41 states.
2008 Iowa picks Huckabee.
2012 Iowa picks Santorum.
Conclusion: Iowa has a pretty bad track record of picking winners. They only correctly picked Dole in 1996 and Bush2 in 2000.