Infuriating isn't it lol.
When that happens to me, I now change my tactics from attacking to defensive and use the possession bonus. Have a look where the gap has been created by the sending off and focus passing in that area. So, if left back sent off, I focus passing down right wing.
I don't know why the game does this - I just know that it does. Making subs and changing tactics seems to counteract the phenomenon though.