Self-healing and sustain on Tank is actually a bit too strong but, it wouldn't be a problem if it wasn't paired with a huge amount of mits and an insane amount of HP.
I mean, waht's the point of having this much of Self-healing/Sustain and this huge HP pool when you can take less than half of them?

You can twist things in any way you want, Tanks need to be nerfed... Not, not nerfed, just put back to a normal level of power.

Too much powercreep is what killed a lot of games.