Problems with warrior tank

Hello everyone, excuses if I’m speaking in the wrong place, but I’m desperate. In the server where I play (3.3.5a) the warrior tank is with a damage default, it is threat (the Slam shield is very low damage), it can not hold the ground like other tanks, I am having difficulty proving that I am Sure, several people are complaining about the same thing where I play, but the GM asks me to be taser like this:

How is it working?
How should it work?

I know the damage of the warrior is very low, but I do not know how I prove that I am right.

My server is based on TrinityCore, but they do not update officially for years, always make updates on their own.

if they use modified core, we cannot help here.