I got to 4389 rating recently playing mostly Ana all soloq. I think a good start would be to nerf her ammo to maybe like 7 instead of 10 where it's at right now. Sitting at 10 ammo rarely puts you in situations where reloading fucks you up big time. By reducing it, you can slowly start regulating this spamclickhealing meta that is Ana right now (not to mention while still having ammo to dps as well). It would create alot more openings where tanks are actually sitting at lower hp pools instead of constantly full hp as it is now. It would also increase the skill ceiling by making players have to manage their target selection more (both offensively and defensively) and time their reloads better. Right now I can pretty much heal up 3 tanks using nade and still have enough ammo to 3 shot some 200hp target - there's almost no punishment for spamming your autos. In fact, I would prefer bringing back the movespeed increase (maybe 20% instead) and nerfing the ammo/fire rate. The movespeed needs to come back because the meta needs to start offering more movespeed increases as opposed to lucio being the sole speed up guy. There are other ways to nerf beyblade instead of just taking speed away. You can simply do an all around numbers nerf of dmg/dmg reduction/speed to do this, but nerfing movespeed was a step in the wrong direction for future meta-building.

In terms of the nade impact, I'm not sure the damage is necessary - it puts her in a spot where she's rarely afraid of any duels and essentially makes her way more threatening of a target for a flankers than she should be considering what she is already capable of. Anas should be rewarded for sleeping a flanker (as true to her high ceiling design), not looking down and pressing E in the most complete no skill way possible and making any flanker abort their position.

A big reason for this happening is because hero design tends to get more complex after initial launch (which is why games tend to have many hero redesigns for the early releases), and the devs are counting on the harder mechanics to compensate for these newer, cooler abilities. The better thing to do is to add more dimensions of play (which is what makes Ana such a fun designed and fun to play hero) to the older heroes like mercy and maybe even zen. The mechanics introduced with Ana (sleep, no healing) needs to stay (again, for future meta building/diversity), they just need to add equally multidimensional ways of playing to the current healers.