When Fox News announced on Wednesday that it would limit participation in the first debate of the Republican calendar to the top 10 candidates in national polling, it was instantaneously obvious that there would be friction.

And sure enough, within 24 hours Rick Santorum (who would not make the top-ten cut, if it were today) offered a complaint. But a good one.

"In January of 2012," he said at a conference in Oklahoma, "I was at 4 percent in the national polls, and I won the Iowa caucuses. I don't know if I was last in the polls, but I was pretty close to last."

He was not last in polls. He was indeed close to last -- at least in Real Clear Politics' polling average.

2012 was different in a lot of ways. (For example, Santorum would have been included in a debate using Fox's rules at that point.) But the more interesting point is: Look what happened to his poll numbers afterward. Within days, he shot up over 15 percent support, and never fell below that level again. Later in the campaign, though, his numbers jumped again -- this time after winning majorities in the Colorado and Minnesota primaries.

From Jan. 3, the date of the Iowa caucus, to March 3, the last contest before Super Tuesday, the winner of each contest went into the next one doing better in the polls.

That makes sense, certainly. Losing candidates drop out and support moves around, for one thing. But also, people gravitate toward candidates they think might actually win. Before Iowa, most people probably wouldn't have included Santorum. Afterward, they would.

Santorum's immediate point was, expand the universe of participants in the debates, because you never know. But he actually did more to undermine his point. Santorum was in all of the debates and still only polled at 4 percent. The debates didn't do much. It took winning to actually make his mark on those numbers.