I think what tcw666 might be asking, is does the attack still go through when Mirror Force destroys the attacking monster. This is a question we get a lot with regards to Sakuretsu Armor.
The answer is simply no, the attack can't go through. When an attacking monster is removed from the field in the Battle Step (which is the only step of Battle Phase Mirror Force can be activated in) then the attack cannot complete.
The Battle Step is the arm of the pitcher. If you remove or damage that arm somehow while he's still pitching, then he never gets to throw the ball. The ball will never reach the plate. The Damage Step is the ball leaving the pitchers hand and heading for the plate. Once he successfully throws that ball, there's nothing you can do to his arm that will make a difference, cause the ball is already in play. Mirror Force can only affect that pitcher's arm (the Battle Step). It's timing is limited to that area of the Battle Phase. If an attack never leaves the pitchers hand (never enters the Damage Step) then the attack never goes though.