bit of history from the iowa cacuses.
santorum won in 2012. obama went unapposed.
huckabee won in 2008. obama won.
then you gotta go back to 1992 to find a difference. tom harkin won for the dems in 1992, and clinton got the nom coming in fourth at 2.8% (tbf, harkin was from iowa)
dick and bob won in 1988, respectively dems and reps, where the third place in both of these got the nomination
in 1980 bush won in iowa, beating reagan.
in 1976, "uncommitted" beat jimmy carter. by 10%. similarly in 1972 "uncommitted" (35.8%) beat edmund muskie (35.5%) and george mcgovern (22.6%)