Because killing on a stacked team doesn't count.

The code of the Anti-Stacker

1. At the beginning of a map that isn't listed below, you should Join the team with the objective.

2. If the map has already started. Join the team that is behind.

3. If the team you are currently on is ahead by more then 4 wins. Change teams as soon as possible.

4. If the team you are on wins 6 rounds in a row (even if they are still behind) change team as soon as possible.

5. Never auto join!. doing so is lame. Doing so, and saying you did it, even more lame. And not doing so and claiming you did, super duper lame.

6. If you finish the map with the highest score on both teams but your team gets thrashed, you must take a screenshot, upload it and post the link on the TG forums or in the group comments!.

Just Remember: Stackers = Go after easy kills = Will kill children for a better KDR.
We must fight these evil child killers.

Team you should join on the following maps:
3rd Street - CT
Atrocity - CT
Aztec - T
Blue Corridor - CT
Chateau - Any
Contra - CT
Dam - CT
Dust 2 - Any
Dust Castle - CT
Inferno - T
Kismayo - T
Los Temple - CT
Menace - CT
Night Fever - Any
Nuke - T
Office - Any
Piranesi - CT
Villa - CT
Westwood - Any

Just a note: The choice of following this code is up to you, but you should try and follow it at least half the time.