As an Alpha training consultant to churches both locally & around the region, I have the privilege of sitting in on many church leaders' and Alpha team meetings. What I always observe is that after a church has launched Alpha and start seeing new believers joining the congregation, the leadership is suddenly faced with a crisis. While they have always wanted the church to grow, they become anxious when they realize that when the church grows through evangelism, church life cannot remain the same as before.
With new people joining the congregation, there is now a desperate search for new leaders and new structures to take care of these new spiritual babes. The old wineskins start to burst at its seams as God pours in new wine. The church has a choice--either to change the wineskins or stay put and let the new wine spills. Some church leadership prefers the status quo and puts an end to Alpha. Despite paying lip-service to evangelism, they actually do not want the church to grow, if church growth means change to the status quo. For such leaders, change challenges their comfort zone and creates a sense of anxiety.
But did not our Lord already warn us that if we want new wine, we must be prepared to have new wineskins to hold it? Just like parenting, when our children arrive, we have to change the ways we have been doing things to accommodate them. So when the church starts begetting new spiritual children, change is inevitable. The leadership that loves the lost will go out of the way to make changes to the church structures in order to assimilate these new believers.