If you think it is bad now, you should have seen it during October and November when people were getting teams they had no business being matched up with GP wise.
Also note on GW: GW doesn't care about team synergy. Phoenix with the same GP as JC lead noob chars makes no difference to the algorithm.
To get a good idea of what you should be facing, check the power of your top 5 characters. That will give you a number that your GW opponents are roughly based off. Battle 1 is 50% or so of that number. Battle 12 is 115% or so of that number. How the opponents characters get there is random. Sometimes they will have superior stars but weak gear, other times stronger gear and lower stars. Sometimes it's raw levels but again weaker gear.