Oh yes, I got flamed by Arrington for predicting it, but diggv4 had to have been some VCs getting hungry for a return they'd expected before the fickle market turned.
http://techcrunch.com/2010/05/29/guy-who-copied-digg-slams-d...
Conversely, Steve and I always talked about 'letting users do the hard stuff.' The more power and ownership we could give them (with guidelines) the more they impressed us. See things like /r/IAMA and /r/Skyrim for a couple examples of genius in idea & execution we alone never could've come up with.
As for traffic, reddit's traffic the Monday before diggv4 was about 600k uniques and 900k the Monday after.
It pretty much skyrocketed from there. Last month reddit had 34M uniques and 2.3B pvs. All after Steve & I left, too. Correlation or causation, I leave up to you.