It is easy to see why such middle ways are so popular. They could lighten the burden on the federal deficit. They could put fewer Americans in harm's way. They would seem to better fit the U.S. interests at stake, which are real but limited and indirect. They appeal to the centrism of many American voters. The problem is that they probably won't work.
The reasons vary from proposal to proposal, but the basic problem is that the pieces of COIN are interconnected and mutually reinforcing. The whole is greater than the sum of the parts; implementing just one or two pieces alone undermines their effectiveness. It might make sense to do less and accept a greater risk of failure, depending on one's tolerance for risk and cost. But there is no magic middle way between the McChrystal recommendation and total withdrawal that offers comparable odds at lower cost. In counterinsurgency, less is not more.