Braves Journal presents a very good post on collusion. I had not thought about the Collective Bargaining Agreement (CBA) in this light before:

2021 will see at least the start of negotiations over a new collective bargaining agreement (CBA).  CBAs are odd because they represent explicit, but legal collusion on the part of teams.  Some part of what might look like collusion over salaries or terms of free agents may actual be the entirely legal attempt by the league to establish a bargaining position in negotiations.  This is a quirk in the very complicated field of multiemployer labor law that I’m not qualified to comment on at the moment. Complicating this is the line in every CBA that owners are not supposed to act in concert. But setting a CBA strategy is of course an implicit exception to this.

BravesJournal.us

The author also points out that some kind of explicit document is needed to prove collusion, such as Peter Ueberroth’s memos in the mid 1980s.