Now that we have the assistant manager (which I think works quite well) would it be possible for them to do a propper assistants job in the abscence of the manager.

If a manager cannot attend a live game would the assistant be able to take control of the match. For example instead of a player having a rubbish game and leaving him on for the full match, the assistant could substitute him and also make changes to the tactics if the starting tactics are'nt working later in the game because the opposing team manager is watching the live match and has made changes.