something along those lines should help:
SELECT DISTINCT
ISNULL(IA.TeamsRSF, 'Not Provided') AS 'Teams RSF'
,ISNULL(IA.TeamSupervisor, 'Not Provided') AS 'Teams Supervisor'
,ISNULL(IA.AssignedWorker, 'Not Provided') AS Worker
,ISNULL(TA.TotalAssignments,0) AS TotalAssignments
,ISNULL(PA.PriorAssigned,0) AS PriorAssigned
,ISNULL(NA.NewAssigned,0) NewAssigned
,ISNULL(CA.Completed,0) Completed