Thats been the norm for years, its not every mission but for some reason it's like this way a lot whenever I personally play missions.
But I know the feeling, it always seems like you're the only one on the team with a brain and a will to fight but your other teamates are so braindead and slow it's painfully obvious which team is going to win the match, almost like it's been pre-decided no matter how good of an effort you put up. And of course, this will affect your K/D in the game, the more low scores you get against premade gold teams in bad matchamking will get you to bronze in no time....
We can only hope that as the game starts getting new content and a big advertising campaign will we start to see a surge of new players to further balance the matchmaking.