Wow. Shocked that Penn would come out against the Clintons–must mean that he sees no future for the Clinton Clan.
I think Penn worked on HRC's 2008 & consulted on her 2016 campaign. IIRC, Mook often ignored Penn's polling in favor of Elan Kriegel's data.
Elan Kriegel & "Ada" is worth digging into.
They thought she would never lose.
https://www.politico.com/magazine/story/2016/09/hillary-clinton-data-campaign-elan-kriegel-214215
https://www.jacobinmag.com/2017/02/hillary-clinton-brexit-trump-algorithm-experts-elites/
https://www.dailykos.com/stories/2016/12/18/1612382/-How-Russia-Interfered-with-the-Election
https://nplusonemag.com/online-only/online-only/confirmation-bias/
https://www.linkedin.com/in/elan-kriegel-235a2087