Answer:
Diminishing marginal product of labor.
Explanation:
Remembering the law of diminishing marginal product which states that by additing unit of labour, while keeping other factors constant would over time lead to lesser output of labour.
Thus one may expect a sports team who continues to add players (additional unit of labour) to its roster above the minimum in the field would eventually not lead to increase efficiency in the field since other factors are kept constant such as increase training for players.