The entire issue with Bouchard was never skill. It was confidence. She has fight, but confidence is a tricky thing. Even the Sedins have commented on how tricky confidence can be.
Even an irrelevant success can boost you up. During her struggles i can still see her making the usual excellent shots. It's the finish. Other players have also adapted to her game, and she needed to adapt as well.
However, i'm not sure if other players adapting to her game affected Bouchard. That's just a guess on my part.