Well, you have to remember Perry is already POTUS of a whole ‘nother country. Texas GDP is bigger than India’s.
He’s used to speaking one-on-one with companies he persuades to move their businesses and employees here, which do.
It’s hard to compress what you do everyday into sound bites or debate zingers. People who excel at saying things are rarely DOers, and vice-versa. That’s why we have spokesmen.
Sorry, but one of the primary, requisite skills for a POTUS, is the ability to speak in a way that is intelligent, convincing, and charismatic. World class leaders do this effortlessly. It's why people follow them, and entrust them with the awesome responsibilities of running a nation.
Even those who seek lesser offices must be able to articulate their views with ease and confidence.
The fact that Rick Perry has demonstrated over and over again that he doesn't have the ability to do this (for whatever reason) is a deal breaker for most voters. His performances in these debates (not to mention some of the positions he's taken) have turned off a huge number of those who formerly supported him (as evidenced by his terrible slide in the polls).
Frankly, the man just isn't inspiring confidence in the voters. On the contrary, he's creating a negative impression, which will be almost impossible for him to turn around now.