Let's include the stated reason for the review: Obama is shocked - shocked! - to learn that there is corruption in Karzai's government:

But the Afghan presidential elections, widely marred by allegations of fraud, undermined the administration’s confidence that it had a reliable partner in President Hamid Karzai. Mr. Obama and Mr. Biden already had raised doubts about Mr. Karzai, which were only exacerbated by the fear that even if he emerges from a runoff election, he will have little credibility with his own people.

“A counterinsurgency strategy can only work if you have a credible and legitimate Afghan partner. That’s in doubt now,” said Bruce O. Riedel, who led the administration’s strategy review of Afghanistan and Pakistan earlier this year. “Part of the reason you are seeing a hesitancy to jump deeper into the pool is that they are looking to see if they can make lemonade out of the lemons we got from the Afghan election.”