be only as strong as the/(one's) weakest link

To have the integrity, quality, or effectiveness of the whole jeopardized or compromised should one single person or element prove to be ineffectual. I need to make sure that everyone on our debate team is well-prepared. We'll only be as strong as our weakest link. A security system is only as strong as the weakest link. It 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 team is only as strong as its weakest link, after all.