The support that's provided to people coming out of jail, first of all, provides stability. One of the largest protective factors against reoffending that I can think of is stability in terms of housing, in terms of relationships, in terms of a place to go during the day to combat isolation, and other sorts of things.
People who have been in jail for 15 or 20 years or more in some cases come out, and they don't know what a bank machine is. They don't know where the food bank is. They may be expected, in many cases, to travel across the city to meet appointments all on the same day. They have no means of transportation, no money, no identification, and no knowledge of how to use the public transit system, so they need stability, stress reduction, support in maintaining medications, going to the hospital, getting a doctor, making sure they take medications, making sure they don't drink, and making sure they appear for their probation and parole appointments. When they get really cranky or angry or fed up or despondent or they fall into despair or say, “My life is not working. I want to go back to jail”, they have people who they can talk to about that and who can talk them through that and talk them into a better frame of mind.