Whitemane is an AoE Healer, so her numbers look higher than they are, due to incidental healing through zeals on targets who have already disengaged, heals that have no impact on the fight’s outcome. Her healing numbers get pretty good as a result, though they’ve dropped significantly since the rework (I’m routinely 30k or so less healing in games than I would have been with pre-rework).
The real problem is Whitemane doesn’t bring much besides her healing. Her spells got nerfed. The talents that boost her spell damage got nerfed. Her primary damage amp got nerfed by 75%. Her armor ult got nerfed and is still not accurate to patchnotes. When you don’t have CC or utility until after everyone has ults and if you choose to go out of your way for it and reduce your healing output, then you need better numbers, and Whitemane doesn’t have better numbers atm, which just results in her feeling weak.
She also feels like a mess because her kit competes with itself and doesn’t really do anything atm.