Of course a secret deal is illegal. There is nothing stopping Alderson from sitting down with Reyes and his agent and explaining that obviously, the team is not going to compete for the playoffs this year and accordingly, the team is considering trading Reyes in order to get some additional prospects back, and that the Mets want to be competitive bidders for Reyes' services once he reaches free agency, and that leveraging Reyes' contract status for some additional players will only result in Jose coming back to a stronger team. That being said, Alderson's first responsibility is to exhaust all possible efforts to sign Reyes to a contract extension NOW.