To my surprise, I actually just ended up explaining how hard manual docking is to a friend?
I'm surprised because A) Z is very smart, and B) I'm *pretty darned sure* he's played plenty of KSP.
Like, dude. Really. You should know all the various things that can go wrong in rendezvousing and docking two space ships. 
(The mission in question was the attempt at docking Soyuz 3 to pre-orbited Soyuz 2, during which Soyuz 3's docking computer failed. Georgi Beregovoy had to attempt to dock manually, and was probably thinking more like a fighter pilot than a space pilot.)