I finally gave up on trying to get a MOE on a tank.

The_Chieftain: I tend to only play a tank until I get my double, then move to the next. As a result, a lot of my vehicles, even those with high win rates, are mucking around the 10% mark. The last week, I've started a concerted effort to MoE one tank in particular. (and it's one I'm good at, over 60% win rate after 200+ battles). My percentage indicated has been going up nicely, currently in the mid 70s. It does seem that a concentrated effort is necessary.