Here are the vote getters in the last several caucuses, FWIW. In instances where there was a non-incumbent, it picked the nominee exactly 50% of the time. Ann used the word :rarely” to describe how often the nominee was the same as the winner. That is a lie. Rush was doing it too. Not sure what his game is though.
2008 – Mike Huckabee (34%), Mitt Romney (25%), Fred Thompson (13%), John McCain (13%), Ron Paul (10%), Rudy Giuliani (4%), and Duncan Hunter (1%)
2004 – George W. Bush (unopposed)
2000 – George W. Bush (41%), Steve Forbes (31%), Alan Keyes (14%), Gary Bauer (9%), John McCain (5%), and Orrin Hatch (1%)
1996 – Bob Dole (26%), Pat Buchanan (23%), Lamar Alexander (18%), Steve Forbes (10%), Phil Gramm (9%), Alan Keyes (7%), Richard Lugar (4%), and Morry Taylor (1%)
1992 – George H. W. Bush (unopposed)
1988 – Bob Dole (37%), Pat Robertson (25%), George H. W. Bush (19%), Jack Kemp (11%), and Pete DuPont (7%)
1984 – Ronald Reagan (unopposed)
1980 – George H. W. Bush (32%), Ronald Reagan (30%), Howard Baker (15%), John Connally (9%), Phil Crane (7%), John B. Anderson (4%), and Bob Dole (2%)
1976 – Gerald Ford and Ronald Reagan
That list shows Bush43 and Ford as the only two nominees in a non-incumbent year to win Iowa. Reagan, Bush41, Dole, and McCain all lost Iowa the year they got the nomination.