The massive movement of intelligence gathering and analyzing forces from Iraq to Afghanistan in the last two years is paying off by cutting Taliban supplies of weapons, and money. More and more captured (often from dead Taliban) weapons and ammunition is of poor quality. Explosives, even the stuff made from ammonium nitrate fertilizer, is harder to get, and often used in smaller quantities in order to make more roadside bombs.
That, in turn, is just getting more Taliban killed, including many more leaders. That's because the largely illiterate Taliban have fewer skilled people for tasks like planting bombs (and rigging them to go off on cue). Guys who get promoted often find themselves one of the few people who knows how to rig a bomb, so they have to go out on the bomb planting missions.
These are increasingly more dangerous because the Americans have more UAVs, along with camera towers and aerostats (tethered blimps) that can see for long distances, day or night and in any weather. It's not just that the cameras can pick up some guys planting a bomb (and call in an air strike), but can detect suspicious movement of any kind.There's much more at the link about how difficult things are getting for the Talibs in Afghanistan and why. Check it out.