While I think all of the above are important, I think it is important to assess the situation. While a team member that is not good at communicating and keeping other team members up to date can certainly make a project more difficult, they may bring a unique skill or talent to the team that is not easily replaceable. In addition, if more than one team member seems to be having an issue communicating with the team, it may be an issue with the way the team is being managed. While in high stress situations it is easy to point fingers and try to remove people from the team, I think good leaders try to instead find out better ways to manage or communicate with specific people. An example is in manufacturing divisions at pharma companies engineers sometimes need to supervise union workers and learn to communicate with them in ways that they will want to listen and support the project. Removing people is not always the best option.