This pollster is pretty bad, as pollsters go.
But Santorum's numbers HAVE fallen, as he's been out of the focus lately given Newt & Perry going after Romney for making money.
Economic conservatives will likely decide those two are crazy, but they are more likely to end up with Romney right now. So Santorum has two opportunities: compete with Mitt for those who believe in free markets, and compete with Perry & Newt for those who emphasize social issues.
He shot up in Iowa for no apparent reason.
He is simply a diversion from the only threat to Romney, Newt.