Interesting question as I wonder this situation (Risk of failure due to interpersonal issues) is often less addressed anywhere. I shall address the situation using formal approach.
Definition of Risk and symptoms: I would consider that the Risk (Project failure due to interpersonal issues within the team or between the team and other stakeholders) is already identified and is listed in the Project Risk register. Next step would be to define the risk and its symptoms i.e when can I say that the project is at risk due to interpersonal issues. The Risk Register would contain the following information to to describe the risk and its symptoms –
Risk Definition : Failure of project due to interpersonal issues within the team or between team and other stakeholders.
Root cause/s : Poor Project Communication stemming out from lack of good interpersonal skills
Risk symptoms : Some of the major symptoms would be –
Uncertainty in project status reporting – Interpersonal issues may lead to lack of reporting of project status within the team and to the top management at the required time periods and in the correct format. This would lead to difficulty in tracking project status and performance.
Project Delays – Inefficient means of interpersonal skills leads to lack of communication (introduces greater noise level) within the team and between team and stakeholders (top management, customers, team lead). This would lead to increase in work trails and activities that leads to schedule overrun and delays.
Increased bug level – Interpersonal issues within the team would lead to inefficient team communication and understanding of system requirements and design. The team member might hit bugs (according to the team lead) very often.
Complaints from unsatisfied customer. – An example situation might be when a team member pays little attention to the customer when he called in to express some concerns with the new version of prototype (especially in agile or extreme programming development environment).
Risk Response strategy: I would recommend ‘Avoid’ strategy to address this risk. We assume that the Risk Identification is done during project planning phase and from past project experience.
Specific Action to implement Risk strategy (Risk response): Create effective communication plan, give adequate interpersonal training to the team members and stakeholders and apply effective motivation within the team so that synergy is increased and interpersonal activities are most vibrant. These actions should be taken prior to project start and throughout the project execution so that the risk is avoided.
Fall back action if specific action fails : If Avoid strategy fails, PM should have a fall back plan to address the issue when the above symptoms show up. One major step would be to address the main constraint resource/s, make them aware of the situation and give them notice to correct their actions. If the resources doesn’t change their ways, PM should also define contingent resources of time and cost available to replace the constraint resource.