Why are balance changes so slow?

Ectar:   Indeed, which is why looking at balance like that doesn't work as what you'll end up with is the same generic tank for all nations at each tier.  You can't give a tank an advantage over another whilst having a drawback because that would be unfair right?  "I would have beaten you if I had your gun depression" etc would still persist otherwise.   The majority of matches the Panther would face off against is going to be other tier VII tanks, any balancing you do for it purely to improve it's performance against tier IX makes it too powerful against tier V and vice versa if it's too powerful against tier V and you nerf it, then it will perform terrible in the tier IX games. It's not as easy as everyone like to think it is when it comes to balancing.