I don't know any more than you guys but from their reputations as leaders and their roles on that team and what we know so far, Cora and Beltran were very likely the two main people doing this on the 2017 HOU team. Cora we know has been the BOS manager the two years since, Beltran I think took off 2018 and then was a 'special adviser' to Cashman from Dec 2018 until just being hired by the Mets (heh Mets).
In light of what we have recently learned, this Cora interview in London this summer after one of the losses to NY is worth listening to again.
View: https://twitter.com/BAT1STA/status/1196228571485933570
I don't know if you could go back to those two games and get any correlation, but he really seems to either be talking about Beltran teaching NY to pull shit for the 2019 edition or Beltran showing NY how to stop Cora's shit. I kind of think it's the latter, but I am also biased.
Edit: Actually I listened again and now I think it's the first, that odd 'devices' mention.