The sentence is:
너한테 필요한 건 키만 크고 얼굴이 여드름 밭인 농구부 주장이 아니야.
According to Naver 밭이다 means to be filtered? Which doesn't really make sense? Or is it like his face was a field of acne?
주장 also means like, assertion? So I guess I'm just confused about the entire sentence.