The scoring hasn't changed. It is definitely NOT hard to rank well. If you're a good fighter stick, you can get a good fighter rank easily. If you like attacking bases in gv's and are reasonably good at it, you can have a good gv rank. If you have nothing better to do on maps like pizza and trinity and decide to go egg something in a buff, you can have a good buff rank easily. If you take a jabo and egg a town and kill a few things, you can have a good attack rank easily.
Ranking doesn't require time; it just requires you to fulfill the categories that are important to rank well (accuracy, k/t, etc).