a chain is only as strong as its weakest link

If one part of something is weak, it jeopardizes the integrity, quality, or effectiveness of the whole. I need to make sure that everyone on our debate team is well-prepared, since a chain is only as strong as its weakest link. A chain is only as strong as its weakest link, and our security will not be effective if any of the checkpoints are not functioning. Yeah, we have a solid team, but we won't win the championship without a top-notch goalie. A chain is only as strong as its weakest link, after all.