Andrew Exum takes a swipe at Greenwald, among others:

I like how pundits who spend their time casting doubt on the assessments and opinions of those with in-depth understanding of Afghanistan and NATO operations there jump at the chance to sing the praises of others with in-depth understanding of Afghanistan and NATO operations when they conveniently advance assessments and opinions that match up with conclusions they themselves have already reached. (Here's but one example.)

Afghanistan and the U.S. presence there is a wicked problem about which many intelligent people can disagree. But suddenly the opinion of a junior State Department employee -- talented and patriotic though he may be -- is the only opinion that matters? So Matthew Koh [sic] is wise but Carter Malkasian and Kael Weston* are what, fools? Or Rory Stewart is clever but Ashraf Ghani and Clare Lockhart are dim? All three are clever, of course, and that's what makes policy options on Afghanistan so devilish. Look, if someone writes something and it matches up with your opinion, by all means say so. But I know about 50 really smart people on Afghanistan with lots of time on the ground there, and no two have the same opinion about what U.S. policy should be. Let's not turn one dude whose opinions on Afghanistan happen to line up with the zeitgeist into the flippin' Delphic oracle.

*To name two people currently doing the same work as Koh [sic] -- in conditions equally tough.

Exum fixed his typo and now has Hoh's name right at least. The trouble is: most of us trying to understand this from a distance have little option but to read and assess views from various experts, carrying various qualifications. We make our judgment based on a variety of factors. In Hoh's case, though, I don't think the impact comes from credentials though. It comes from the sheer content of the letter - its cogency and power and integrity. It makes the most comprehensive sense of our position of any analysis I have read. And it suggests we should leave.