이번 3월 고2 모의고사 20번에 관한 질문입니다.

when the heat of competition is turned up, the individual performer or team that falls apart most often does so because of mental factors like poor concentration, negativity, lack of confidence, or an inability to let go of mistakes.

여기서does so가 fall apart 라는데 왜 그런거죠?? 그리고 does so에 대해서 알려주세요