It's not that simple. I'm still not entirely clear on it, but all sides involved seem to be acting as if there's either a CBA provision or a labor law that forbids teams from acting this way for the reasons the Cubs are doing it. It may be a rule that has never been enforced, but it sure seems to be there. There may be a dispute over the language and what it means. There is no labor law the prevents the authorized bargaining agent from agreeing to language itself. Are you allowed to agree to compensation via metrics, and then game the metrics? Or is that bad faith? Its not "bad faith", but it could be a violation of the terms of the agreement. Most likely a question for an arbitrator, depending on how the CBA operates.