The first three matches are those that have the most impact on your rating (+80 to +50 rating in one match as gw2 efficiency shows) since you won those games you might be higher ratet as you deserve.Also you got probably tilted after such a loosing streak and took more risks than you would do normally (so you probably played worse than in the first 3 games)I wont deny that bad teammates are also a factor, but not the only reason for your loosing streak.