I've watched the first inning of game 1 and 2 a few times over now. It's almost like for game 2, they knew fox's mic's were picking up the whistles. They are a lot fainter, but a few times after I can pick them up.
The pitch 19 in game 1 that was the high fastball that gave them the 2-0 lead had the exact same whistle as the high fastball in pitch 13 in game 2 that ended up higher than high and you could see Brantley wanting to go for it and laying off.
The change up Bregman got in game 1, inning 1 to strike him out has a very distinctive whistle. He knew that one was coming, but still swung and missed. It's fainter in game 2, but you can hear the same whistle pattern on the change up Bregman hits out of the park in the first inning of game 2.
Watching those 4 pitches over and over, I have no doubt they knew high fastballs were coming and that the change up was coming, and that accounted for all 4 RBIs in the first 2 innings of those games.
If they were using cameras and technologies to be able to relay that detail of what pitch was coming, and I really don't know how else they could be doing it, that's a significant step up on any cheating that has happened before in pro sports.