Yes, Perry has not articulated a plan like Cain or Gingrich but he usually takes the position that government is the problem not the solution. As long as you understand and live by that principle then a “plan” can always be done later.
That being said I think it’s the detail that Cain and Gingrich have laid out that is boosting them in the polls.
Perry is leaving a vacuum that allows his critics to define him.
Every politician is going to have good and bad in his record. Not laying out an agenda allows the critics to focus on the bad parts and ignore any good parts