We used to use the expression, "There's always that 10%," a lot. Personally, I think that's BS, and that it's more like 1-2%. Meaning that, out of all the Marines you'll deal with, there will always be that 1-2% who have slipped through the cracks. Of course, that 1-2% was basically my entire first squadron when I was enlisted, but that's another story.
Anyway, while this might be true on the enlisted side, I think the general screening for OCS/USNA/ROTC/etc. cuts this number way, way back in the officer ranks. But I'm a firm believer that there will always exist "That Guy," and really the only way to reign he/she in is some superior peer leadership (yes, the hardest type) and a good CO/XO/SgtMaj tag team.
From the little I've read from the book, and from what I've heard about Swofford from people who served with him, he definitely falls into that 1-2% category, and it's a shame. The guy's obviously got some smarts if he's going to get himself book and movie deals, so just imagine if someone had been able to find the right combination of positive v. negative reinforcement and leadership to help this guy shine.
I think that I do have to agree with A4s, though, this guy's a sh!t.