What is this stripe?

The_Chieftain: Technically, they indicate merely damage caused, not overall performance. It is, in theory, possible to have three marks of excellence, indicating that you have caused more damage per game in that type of vehicle than 95% of the other players, while still losing 95% of your games, as it reflects purely damage done, and not where and when you did that damage. Of course, in reality, there is a reasonable correlation between the two, but there is a nasty tendency for people to purely associate damage done with competence. (Caused 4,000 damage, lost game, my team mates were idiots!)