What is middle reliever?

A middle reliever is a relief pitcher in baseball who typically appears in the middle innings of a game, after the starting pitcher has left the game and before the closer comes in to finish the game. Their primary role is to hold the lead or keep the game close until the closer can take over. Middle relievers are also referred to as "setup men" because they set up the closer to come in and finish the game. They usually pitch 1-2 innings, and their main goal is to throw strikes and get outs. They are often used in situations where the game is still winnable, but the starting pitcher has been removed due to fatigue or ineffectiveness. Middle relievers can be an important part of a team's success, as they provide valuable relief innings and keep the team in the game.