https://wikileaks.org/podesta-emails/emailid/34899
This is the stats page for the bit.ly phishing link from that email showing two clicks in the right time frame:
It's not rocket science to dump the emails out of a Gmail account:
https://support.google.com/accounts/answer/3024190?hl=en
But the Podesta leaks aren't the same as the DNC leaks, which Wikileaks has long claimed came from an insider who was upset by their treatment of Bernie. It's also interesting to note that even if the DNC was hacked, that doesn't actually prove where the information given to Wikileaks came from.
Given how careless they are in other regards, I have to think that any insider that wants it can get their data. Just read the PDF on this email to see how Colin Powell & Hillary Clinton treat OPSEC: https://wikileaks.org/clinton-emails/emailid/30324
"When I asked why not they gave me all kinds of nonsense about how they gave out signals that could be read by spies, etc. Same reason they tried to keep mobile phones out of the suite. I had numerous meetings with them. We even opened one up for them to try to explain to me why it was more dangerous than say, a remote control for one of the many tvs in the suite. Or something embedded in my shoe heel. They never satisfied me and NSA/CIA wouldn't back off. So, we just went about our business and stopped asking. I had an ancient version of a PDA and used it. In general, the suite was so sealed that it is hard to get signals in or out wirelessly."
Also, the DNC has long been planning to reach for the Putin angle:
"Best approach is to slaughter Donald for his bromance with Putin, but not go too far betting on Putin re Syria. Brent"
With computer crime it's especially obvious because most journalists don't know enough to understand what's hard and what's not, so they take the word of law enforcement, and law enforcement has big motivation to make it sound as bad as possible, since it enhances their significance and their success for catching one. "I've caught a sophisticated hacker" sounds better than "I've found a 13-year old kid that sent someone an email saying 'give me your password' and the poor shmoe was silly enough to do just that".
So there won't be a lot of reports about catching unsophisticated hackers. Usually it's always "highly sophisticated" ones.
OTOH, I think the actual (claimed) proof was using of certain bit.ly account etc. not sophistication per se.
Also, it looks like there were at least 3 attacks on the DNC, and phishing was only involved in one. Maybe the whitepapers talked about the other ones.