or you get in one of those rare matches where the other team is being F**king idiots and lets you get this
the key to this achievement is based around communication. Often times teammates see that one area is "under attack" which causes most of the team to rally around that area. This leaves the other area vulnerable and starts a vicious cycle that will cause you to lose the first phase. Make sure the teams are spread out enough to monitor the areas from different angles. also, make sure skill levels are about even at the different areas. If this means having 2 people at an area and 4 at the other, so be it. Do whatever it takes to defend the areas and you'll get the bleep bloop!!!