The point is that as long as Ron Paul is out there on the political flank of plausible candidates with a small committed support base, the more centrist candidates will tack towards his position to try and capture some of his support.
do you have any example to support this claim? Ron Paul isn't running for the first time. Which of his positions got anywhere close to mainstream candidate's agenda previously?
Witness how Santorum pulled Romney towards more socially conservative positions just by existing.
Santorum was Romney's runner-up if not outrunning him during several moments.