The rules cited were Section 4 of the National Agreement and Section 7 of the Constitution of the American Association:
Section 4, of articles of qualified admission to the national agreement reads:
"Any player under contract or reservation or who shall be expelled, blacklisted, suspended or rendered ineligible by either of the parties of the first part or the Board of Arbitration, shall be ineligible to sign or play with any of the clubs members of the associations parties of the second part herein; and any club which shall knowingly play any such player in their club shall be dismissed from membership by the association of which it is a member, or said association shall forfeit all rights under this agreement."
Section 7 of the constitution of the American Association says that "upon the release of a player from contract or reservation with any American Association club, his services shall be exclusively subject to the American Association club that shall, within ten days from the date of release, signify in writing or by telegraph its desire to secure the services of the player. If more than one Association club signifies a desire to secure the services of a released player within ten days and no written or telegraphic assent of said player to contract with either of the clubs be filed with the President, then the disinterested clubs of the Association shall by vote, taken by telegraph, mail or ballot, determine which of the clubs shall be entitled to the player's services, and in the event of a tie vote the President shall decide."
In general terms, for Devlin to be transferred to the Whites, the Browns would first need to get the approval of all the other clubs in the American Association. And while Staley could be transferred to the Browns more easily, he would not be able to be transferred back easily for the same reasons.