A middle field goal block in football is when a defensive player comes through the middle of the offensive line to block a field goal. The defensive player is responsible for putting a lot of pressure on the kicker after the kick is performed. However, it can be hard to try to block the kick when the kicker's team is trying to keep everyone away from the kicker.
The strongest pass rusher is typically positioned in the middle of the line. His goal is to break through the blocking line in hopes to hit the ball mid air, deflecting it from going into the goal. The pass rusher jumps with his arms up, hoping to get even a finger on the ball, because every bit of force on the ball can change the trajectory and direction of the ball.
The pass rusher is most likely to get a hand on the ball if the kicker's trajectory is off from the start of the kick. If the kicker is feeling a lot of pressure or hits the ball slightly differently, it can not send the ball as high, meaning the defender could block it. Blocking a field goal isn't very common, but it can be critical for teams who are trailing by just a few points.