Fallows' insight:
Romney is very strong as a debater but has also shown two repeated weaknesses: a thin command of policy details, and an awkwardness when taken by surprise.
When the subject is one he’s prepared for, he rarely falters. When it’s not, or when an exchange goes on longer or in a different direction than expected, many of his ad-libbed responses turn out to be mistakes ("I’ll bet you $10,000!"). Thus the Romney team has the impossible challenge of trying to imagine every question or attack line that might come up in debates with Obama, while the Obama team tries to imagine what Romney’s might have missed. This kind of chess game is always part of debate preparation, but it is unusually important this year, because the gap between Romney at his best and at his worst is so wide.
The Dish 