This article is from July 26. Two weeks later, the Taliban had taken Kandihar a strategic focal point for the Afghans and the US. Air support wasn't winning the war at that time.
The United States will to continue to carry out airstrikes to support Afghan forces facing attack from the insurgent Taliban, a regional U.S. commander said on Sunday as U.S. and other international forces have drawn down troops in Afghanistan.
www.reuters.com
Here's a question... If American troops were fighting for their homes and the safety of their families, do you think they would give up even if they lost support of their airforce? Heck the Germans (famously dependent on Luftwafa support) kept fighting for months after we had control of the skies in WWII and many of those were young kids and old men.
I just don't believe that the Afghan army had the discipline or the desire to fight the Taliban. Many of them were simply bribed to leave their positions.