noun
scout player; placeholder starter
Baseball term: a player listed in the starting lineup to be replaced once the opposing starting pitcher is known, allowing the manager to adjust the lineup.
今日の試合では、偵察要員として控えの選手がスタメンに名を連ねている。
In today's game, a reserve player is listed as a starter as a scout player.
Compound of 偵察 (scouting, reconnaissance) and 要員 (necessary personnel, member). The term is specific to baseball strategy.