Below are quotes from the espn article linked:

“The memo, according to sources, included a line that said: "Finally, each Club's General Manager and Field Manager will be held accountable for ensuring that the rules outlined in this memorandum are followed by players and Club personnel."

This is a vitally important sentence, because with it MLB placed the onus on teams — and, in the Astros' case, general manager Jeff Luhnow and manager AJ Hinch — to alert players that they would face discipline if caught using technology to steal signs. During MLB's investigation into the Astros' sign stealing, the league learned, according to a report Manfred issued in January, that "Luhnow failed to take any adequate steps to ensure that his Club was in compliance with the rules." Similarly, players interviewed said Hinch had not informed them of the potential for discipline.”

LATER IN THE ARTICLE.....

“Four labor lawyers with first-hand knowledge of the grievance process agreed: the lack of notice from the Astros to their players would have made any case pursued by the league practically DOA. Yes, grievance hearings do now and again end with surprising results, but the probability tilted significantly toward any potential suspension being overturned, the lawyers said.”