Join in Progress is terrible

I’ve joined countless games now where the game is almost over and the enemy team is 15+ kills above my team. Why is this happening? I thought it was stated earlier on that there is a formula for Join in Progress that would prevent these kinds of matchups from happening? If there is, it isn’t working and it is greatly diminishing my morale to play this game much longer. I just want to join a game from the start, not right before we get our guaranteed loss.