If you are 3-4 down and double, your opponent should refuse the double even if only slightly behind, since that is a chance to even up the game again (rather than continue the current game at a disadvantage).
Hence it is important to double before the game gets going.
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)