Ah, thanks for that. Hadn't seen the PhD reference...is that in "Even Hand"? That and "AAAA Wizardry" are the only Dresden stories I haven't read. I'm still a fairly new fan to the series, ate up the case files and side jobs in one stretch without spending a day not reading at least a good chunk of chapters. It's both weird and fun how much stuff you pick up rereading when you're not fatigued.
Interesting theory for Marcone's absence. Adds up really nicely too, but for some reason it just doesn't feel right. Can't put my finger on why and time (and JB) may well prove that intuition to be wrong, but it just doesn't seem to jive. I have no reasonable discussion points beyond my gut feeling on that one.
Just as a note on Hendrick's skill set, it's a very good point that one shouldn't judge intellect by appearance, but similarly intellect alone does not make a people person. Case in point; Butters. Yeah, his relationship with Bob makes him a great lookout, but let's be honest, in a serious negotiation he'd be pretty much useless. He's quite possibly the smartest character in the series, but he lacks many other skills in regards to the application of that knowledge.
Same thing for Hendricks. He may be freakishly intelligent, but his demeanor towards conversation, negotiation and compromise seems to make him a dubious choice as an envoy/ambassador at best. Granted, Harry hasn't seen him in that many situations and he has good reason to be on his guard with the wizard. But then, when representing a Freehold Lord in supernatural affairs or a plain vanilla crime boss, how many instances could he really not be on his guard? If the way he reacts to Harry is typical of the way he reacts to anyone who might threaten or challenge Marcone, negotiating just ain't his thing.