Runes make all the difference.
I have a great Zombie for instance! 160 dodge, 1700 armor and lots of other stuff makes him really hard to kill.
And my Roller is awesome, which has nothing to do with dodge. She's tweaked differently, and delivers devastating damage!
If your Tank dies too easily, prioritise defensive stats and let those that are protected by the Tank do the damage.
Lots of damage, life steal and tenacity will increase survivability while retaining damage, but won't work well with all of them.
If you use Fury, don't put too much defensive stuff on, as you need to take damage for it to work.
There are many ways to make use of the Tanks as they are, although DLady is rubbish and I am very happy that I left her behind early on.
What new rune system? The one that has been suggested here but never been acknowledged by the game team? Don't hold your breath, learn how to use the current one instead. It Does work, and by using it cleverly I am competing with players who have a much higher level and power, and who spend a Lot more money than I do.