In de-norming, which is a reversal of the storming phase, the team's comfort level decreases. Team cohesion weakens as more group members resist conforming to team norms and quit participating in team activities. Angry emotions flare as the group explodes in conflict and moves in to the final stage of de-forming.
In de-forming, which is a reversal of the forming stage,team members position themselves to gain control of pieces of the team. Team members begin to avoid each other and isolate themselves form team leaders. Team performance rapidly declines as the members quit caring about even minimal requirements of team performance.
If teams are actively managed, decline is not inevitable. However, managers need to recognize that the forces at work in the de-norming, de-storming, and de-forming stages represent a powerful, disruptive, and real threat to teams that have finally made it to the performing stage. Getting to the performing stage is half the battle. Staying there is the second half.