If the strategy is looking at "what most people use" and "what is overrepresented in the win stats" you will always end up nerfing what is fun and popular.
So I'd suggest smaller changes.. off course fix bugs and stuff that does not work as intended.. but balance a weapon .. and go on to the next. Also decide what a weapon is supposed to do.. sniper shotguns should not exist.. neither CQB dmr's.