I'm not a infantry tactics person, but this WoTR article struck a chord:
What has been overlooked in the debate over the combat potential of violent extremists is the diffusion of something much more rudimentary and potentially more lethal: basic infantry skills.
This strategy will not change. We do, however, argue that the marginal improvement of tactical prowess in violent non-state groups may lead to outcomes that have strategic implications for global U.S. counter-terrorist and counter-insurgent operations in two other ways.
In sum, improved tactical prowess may open the door for strategic success for these (insurgent / terrorist) groups, despite their continued inability to defeat U.S. forces in conventional battle.

I could not readily find a similar thread, although those on IEDs follow the theme.

The authors have many points and even some answers, for example:
As a consequence, the U.S. military should stop being one of the best suppliers of tactical instruction to the bad guys.