Sloane Stephens,for example. I don't know what you see as 'in form' player, if that's someone who's not injured and play well even though they do not win events or only those who are in the elite and winning many tournaments. I see it as the first option.
Her game is OK now, she can come back from behind sometimes although still cannot do that against the best.
I think winning an international/Premier event is a pretty realistic goal for someone in top 20. Competition is not always tough,especially at new venues.
After losing to Ana at the USO Sloane Stephens spent months away from the courts. Why? She had a big tear in the abdomen during that tournament. The match before that, Sloane was taken to 7-5 in the third by Tatiana Malek. Sorry, can't count Slone as an in form player at that time.
In form is anyone playing remotely well.
Ana's game is worthless.. harmless.. she has no weapons.. that's not ok at all. She wins matches by being stable, meaning the other player gifts enough points. But she isn't fast enough, or has a good enough FH (and it was once one of the best in the game! How things have fallen!), serve is craptastic..
So yes.. she can be a journeywoman, maybe top 20 forever, she will face enough players she can beat by being more stable. But winning tournaments? Sorry.. no, no matter what the tournament is, there will always be someone remotely in form, enough to beat the stable game.
To have any significant win, or to get any title, Ana would actually have to go back to a game that brings her weapons to life.