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Commissioner Guide: Investigation Decision Trees for Cheating and Collusion

Most fantasy leagues run for years without a major integrity issue. When one arises, the commissioner who acts on accusation rather than evidence damages the league as much as the cheating does. The commissioner who follows a systematic process earns long-term credibility — even when specific managers disagree with a specific outcome.

The Foundational Rule

Accusation is not evidence. Suspicion is not evidence. A bad trade is not evidence.

Before taking any action:

  1. Gather the full data
  2. Investigate both parties separately
  3. Look for patterns, not single incidents
  4. Apply the same standard you’d use if the accused were your friend

Decision Tree: Trade Collusion

A manager claims another manager is trading lopsided deals on purpose to benefit a friend.

Step 1: Pull the full trade history between the two managers.

Are there 2+ lopsided trades between the same two managers?
  NO  → Single lopsided trades are not collusion. People make bad trades.
         → Respond: "One trade that looks bad is not collusion. I looked at
            the full history and this doesn't show a pattern."
  YES → Continue to Step 2.

Step 2: Does the selling manager have a plausible innocent explanation?

Contact the selling manager privately. Ask: "Can you explain the reasoning
behind [these trades]?" without revealing the complaint.

  Plausible explanation exists (sell-high, positional need, wrong valuation)?
    YES → Note the explanation. Does the buying manager's story align?
          Contact the buying manager separately and ask about their side.
          Stories align? → Likely innocent bad trades. No action.
          Stories conflict significantly? → Continue to Step 3.
    NO  → Continue to Step 3.

Step 3: Is there any corroborating evidence beyond the trades?

Examples of corroborating evidence:
  - Both managers known to coordinate outside the platform (friends who openly
    discuss strategy in real life, shared league communication)
  - Pattern of trades where the "winning" manager always benefits
  - Buying manager recently received help in the same week he benefited

  YES → This is a supported collusion investigation.
         → Veto the most recent lopsided trade.
         → Issue a formal warning to both managers.
         → Document everything.
         → One more incident = removal from the league.
  NO  → Evidence is insufficient. No action beyond monitoring.
         → Respond: "I investigated and found suspicious trades but no
            evidence of intentional collusion. I'm monitoring the situation."

Decision Tree: Tanking (Deliberate Losing)

A manager is suspected of intentionally losing games to improve their draft pick position.

Step 1: Review the manager's lineup decisions over the past 3+ weeks.

Are they consistently starting injured, inactive, or clearly inferior players?
  NO  → This is bad management, not tanking. People lose because they play
         poorly or make mistakes — not every poor lineup is intentional.
         No action. Offer help if they seem disengaged.
  YES → Continue to Step 2.

Step 2: Check waiver wire activity.

Has the manager been making waiver adds when key players got injured?
  YES (adds match injuries) → Manager is trying to compete but failing.
                               No tanking evidence. No action.
  NO (sitting with clear holes unfilled for 2+ weeks) → Continue to Step 3.

Step 3: Contact the manager directly.

Send a private message: "I noticed your lineup has had some issues for
the last few weeks. Is everything okay? Do you need help with the platform?"

Manager responds and explains (busy, confused, personal situation)?
  YES → Give the benefit of the doubt. Monitor going forward.
         Set a 1-warning policy: one more neglected week = league rule invoked.
  NO response or dismissive response → Continue to enforcement.

Step 4: Apply your active lineup rule.

Do you have an "active lineup" rule in your constitution?
  YES → Enforce it: the stated consequence (pick forfeiture, fine, warning).
  NO  → Issue a formal warning. Update the constitution immediately with:
         "Managers must start a full lineup with available (non-IR, non-bye)
          players every week. First offense: warning. Second: loss of last-round
          draft pick. Third: removal from league."

Decision Tree: Account Sharing / External Help

A manager’s lineup quality has dramatically improved, or it appears multiple people are making decisions for one team.

Is there direct evidence of account sharing?
  Examples: Screenshots showing multiple people discussing one team's lineup,
  a manager openly admitting they got help from a third party,
  IP/device logs showing logins from multiple locations (if platform provides this).

  YES → This is clear grounds for action.
         → Warning with explicit no-account-sharing rule stated
         → Second occurrence: removal from league
  NO  → Is the "improvement" explainable by external factors?
         Did the manager hire a fantasy service, start reading expert analysis,
         or simply improve their skills?
         YES → This is legal and cannot be prohibited. Any manager can
                use published expert advice. No action.
         NO  → You have suspicion but no evidence.
                → No punishment. Add an explicit constitution rule prohibiting
                   account sharing. Monitor for further evidence.

Communication Scripts

When you find no evidence to act on:

“I investigated [the situation] carefully, including reviewing [specific data]. I didn’t find evidence of [collusion/tanking/cheating] beyond what I’d expect from normal mistakes. I’m going to continue monitoring. If you see additional specific evidence, bring it to me.”

When you take action (veto or warning):

“After reviewing [the specific data], I’ve decided to [veto this trade / issue a formal warning]. Here’s what I found: [specific facts]. Here’s the rule I’m applying: [specific rule]. This decision is final. Going forward, [what changes].”

When you expel a manager:

Never announce expulsions in the group chat. Contact the expelled manager privately first. Then post to the league: “I’ve made a roster change for River City Rebuild. Jordan is joining the league. I investigated an integrity issue and took the necessary action. Happy to discuss with anyone privately.”

Preventing Problems Before They Start

Publish an integrity section in your league constitution that covers:

  • Definition of collusion (what it is and isn’t)
  • Active lineup requirements (every week, all positions filled with available players)
  • Tanking definition and consequences
  • Account sharing prohibition
  • The investigation process (evidence-based, both parties heard)
  • Available consequences in order: warning → trade veto → pick forfeiture → removal

Set the tone at season start: A commissioner who enforces rules consistently and without favoritism discourages exploits. A commissioner who lets things slide for friends breeds resentment and eventual bad-faith behavior.

Manager selection matters more than rules: The best prevention is inviting managers who play the game in good faith. No rulebook prevents someone determined to cheat from finding a workaround — good culture does.

For building the constitution that prevents these situations from arising, see: Commissioner League Constitution Guide. For disputes that don’t rise to the integrity level, see: Commissioner: Handling Disputes and Protests.