Now imagine a team of five people working on a project, and each one of them has a set of tasks to accomplish, these tasks are intertwined and interdependent. With each one of the team members experiencing just one defect out of 10 activities means we have a total of 5 or less defects out of 50. If these activities are coupled and some could be common the actual impact is equivalent to more than just 5 defects out of 50, worse case is 5 defects out of 10 if all tasks are common across the team, which equates to an F.
Teams members need to not just achieve grade A quality, but reach above and beyond an A, to allow the team to strive for an A grade satisfaction and excellence.