If the Chiefs are, as they seem to be, upset by the alleged failure of agent Steve Weinberg to honor an agreement in principle for receiver Emmanuel Sanders, the Chiefs can do something other than complain about it.
While the agreement isn’t binding until it’s in writing, all parties to the Collective Bargaining Agreement have an obligation to negotiate in good faith. Article 4, Section 8(a) imposes that obligation on any team, player, or player agent engaged in contract negotiations.
The argument would be that Weinberg failed to engage in good faith negotiations by conducting talks with the Chiefs despite having no intention to finalize the discussions. The grievance process could result in a conclusion that, if sufficient proof exists of an agreement in principle, failure to proceed to the signing of a contract without a reasonable excuse necessarily becomes evidence of bad faith.
Of course, that would be a dangerous precedent for the various NFL teams to set, since it would expose them to similar grievances in the future, if they strike an agreement in principle and fail to honor it.
Either way, the Chiefs have an alternative to venting in an off-the-record fashion. If the Chiefs believe they were screwed by Weinberg and Sanders, they could file a grievance and force this supposedly sordid side of the business into the light of day.