So your "guess" is based on supposition, right? You don't know that the NSA doesn't have hard evidence, you suppose they do not because they have not shown it to you.If the government has proof that "the Russians" stole the DNC emails and released them through Wikileaks, why haven't they indicted Assange for "collusion" to interfere in the 2016 election?
Do you suppose the government's case against "Russia" is based on supposition and not on any hard evidence? That's my guess. They have proof the Russians hacked the network, and were on it when the emails were stolen, but none that they actually downloaded the emails and/or that they sent them to Assange. Considering that the NSA has archived all internet traffic logs, that part should be easy, right? So what's the hold up?
What do you "suppose" internet logs would show? Do you really think that every movie or download from one system to another is archived? Having seen logs kept by credit card processors, banks, telephone companies...I can tell you that they may keep the metadata...that from IP address to IP address a file was sent and it was 5gb at a given date and time. Keeping content would be impossible.
One other item...would the NSA reveal how much they actually capture?