In his column Sunday, George Will wrote:

The Ames poll has not reliably predicted the winner of Iowa’s caucuses five months later, and the caucuses have been an uncertain trumpet regarding the winner of the nomination. In 1979, George H.W. Bush won the poll and the subsequent caucuses but lost the nomination to Ronald Reagan. In 1987, Pat Robertson won the poll, Bob Dole won the caucuses and Bush won the nomination. In 1995, Phil Gramm and Bob Dole tied in the poll, then Dole won the caucuses and the nomination. In 1999, George W. Bush won the poll, the caucuses and the nomination. In 2007, Romney won the poll, Mike Huckabee won the caucuses and John McCain won the nomination.

All true, but Will leaves out some important context demonstrating Iowa’s significance. In 1979, George H.W. Bush was roughly where Jon Huntsman is in the Republican race this year. Winning Ames and then Iowa launched him toward a second-place finish and made possible his spot on the ticket with Ronald Reagan. Ames and Iowa similarly established, however briefly, Pat Robertson as a force in the 1988 contest — and the GOP throughout the 1990s.

Phil Gramm’s inability to finish ahead of Bob Dole at Ames was an early signal that he wasn’t going to be successful as the conservative alternative to Dole. By the time the caucuses rolled around, Pat Buchanan had clearly secured that role. Ames helped knock Dan Quayle and Elizabeth Dole from the 2000 race, giving George W. Bush a clearer path to the nomination. Mike Huckabee’s strong second place showing at Ames was crucial to upsetting Mitt Romney in the caucuses, which in turn derailed Romney’s most plausible path to the nomination.

Even when the straw poll and the caucuses haven’t predicted the nominee, they have played a large role in shaping the outcome in recent years.