Thats because the American went off on their adventure in Iraq... Also, besides the fact that the Taliban have only regained some steam after a number of years following their defeat in Afghanistan, the US cant fight terrorists hiding in FATA... Hence the need to train Pakistani forces to do the job.
2nd adventure (Iraq) is really no excuse, US always have "satellite" to monitor any movement in/out of Pakistan. They can track Mullah Omar running away on a motorcycle in mountains so why can't they track arms/ammo movement by Taliban insurgency in/out of Pakistan. Taliban didn't pickup steam after a lapse of few years, US/coalition never had full control of Afghanistan in 7 years.
Otherwise, the US has been pretty succesful in its anti insurgency efforsts. The Surge in Iraq obviously worked (as much as I hate to admit it), and the drone attacks within Pak have killed some really big name terrorists.
In case you didn't read related articles, ever since drone attacks in Pakistan picked up pace militants have moved from Iraq and other parts of Afghanistan towards Pak-Afg border, thats why insurgency in Iraq has faded. I agree drone attacks have probably killed some legitimate targets but then that is not this "special training" will be for, US will not be handing over drones to Pakistan to fight against Taliban/AlQaida.