No, she doesnt have tank stats nor def abilities, nor counter. Considering any girl with Evasion skill as a off tank is a wrong way to look at it.
Kerria is pretty much and always has been pure DPS. She has the highest damage output when Bloomed due to all the self buffs she applies.
While Mei Plumblossom has the highest Damage skill (5.2) multiplier, the sheer amount of damage that Kerria adds to her attack puts her ahead by a lot. And then add the Life drain (if she procs the Ult, she can pretty much heal her full HP, especially if it Crits > crits dont yet work in Nutaku versie, though the red numbers that symbolise them are in.)
The fact she has Evade is more of a "extra" in her case.