As a deputy, assistant manager, backup quarterback, or other fill-in, there is a key ingredient in success. You’re not the actual boss. You’re not the actual quarterback. In the life stories of the venerable Companions of the Holy Prophet, upon whom be blessings and peace, who were made deputies there is a similar theme, albeit very religious: these deputies did not have Wahy (Divine Revelation). Although there is a measure of inspiration based in faith (firasa) and spiritual unveiling (kashf) that the grand Companions had, the authoritative Revelation provided to the Holy Prophet to answer questions and give religious guidance was not active.
So, as a deputy or backup, one must be as close to the tradition as possible (playbook) with the following self awareness: 1) you do not have excellent subordinates such as yourself underneath you; and 2) you have your own gifts and style.
Be aware. Use the precedents, the playbook, and your own God-given gifts to fulfill your duties.
Ibn Sa’d said: The Messenger of Allah, may Allah bless him and grant him peace, appointed [the venerable ‘Uthman ibn ‘Affan] as his deputy in charge of Madinah during the military expeditions to Dhat ar-Riqa’ and Ghatafan.