I don't see what Wikileaks has to do with polling, but YMMV.
We know that Assange has an agenda - he has said that wants to defeat Hillary. We can't trust anything that he releases to be objective. (Doesn't mean it isn't, it's just we can't trust it.)
The original story you pointed to had the writer saying that things were "obvious" when in fact they aren't. Previous "leaked" (actually stolen) e-mails from Hillary's people were forwards of stories published in the press but were spun as things that Podesta (or some other big-wig) had said. It's dishonest to spin things that way.
Given those things, it's hard for me to see what you want me to comment on.
How is anyone in the Clinton campaign "manipulating" polls? This is more flailing by people who don't accept the results (just like Rmoney's people were "unskewing" polls in 2012). Even
Rove is saying that Trump can't win.
Anything can look nefarious when taken out of context and when spun by people with an agenda. Remember Shirley Sherrod?
I'm happy to discuss almost anything with you, but you know what gets my Spidey-Sense tingling. If you don't want me to respond that way, then pick a better source. ;-)
Cheers,
Scott.