Cache is probably easiest of all maps to rank up fast on because you can singlehandedly carry your team on that map because it doesn't rely heavily on teamplay because of the open sites, mid area and the ability to do quick rotations. DD2 is like that as well, but its so heavily played that its just harder to get the frags on. I would argue that you can also carry your team pretty well on overpass if you go towards A and underground rather than going in to b solo.