If you are talking about the Foch (Tier 9) it is a bit more of an argument, but considering everyone knows the Foch 155 is OP, you're clutching at straws.
-It's turn rate is far too quick, most tier 9 and 10 mediums have a hard job flanking it. They're mediums...
-It's frontal armour is ridiculously hard to penetrate. The "weak spot" doesn't even appear to exist either
-It can get from one end of the map to the other pretty quickly. The mobility is really good.
-It's an autoloader, which are inherently overpowered as it is. All you need to do is blast off shots and go and hide for 40 seconds (depending on the autoload speed), come back, trash whatever you meet and vanish again.
Nerf the turn rate a little, so it can be flanked and make the weak spot into an actual weak spot and it'll be much better, but right now it is certainly overpowered.
The new TD looks to be the same thing, as Hodders says, watch gold spent to get to it, then nerf later. Rinse and repeat. Kind of losing faith in Wargaming's "balance" abilities.