It isn't like it is classified. Anyway I have a collection of law enforcement training documents and other manuals and statistics relating to them, and I believe in one of the career path papers I have from FBI it says they start teaching their agents traffic analysis after 8 years at quantico if they go down the cyber crime career path. It isn't like the FBI doesn't have anyone who knows anything about traffic analysis working for them, although in 2008 they did fail to trace Tor clients that were used by a group of violent pedophiles including ones who were posting new material. Then again, tracing clients is a more impressive feat than hidden services, and they got many of the pedos who were using VPN's or posting pictures via photographic forensics.