Yeah, Svitolina and Beck are currently better, no doubt. They are also at least 2 years older than Anett and in top 200, so no surprise there. I have no idea about Vekic, those 25k-s she won (or got to the finals) were pretty weak overall, but she did defeat a bunch of top 250 players. Depends on the surface also I guess.
We should wait until these 3 tournaments are over (RG, Roehampton and Wimbledon) to draw any conclusions about Anett being in a slump or sth.
That's why I mentioned they are better in this very moment. A two years difference is important at this age. Anett may become a better player than Beck and Svitolina in the future. As for Donna, I'm really curious how she'll cope with stronger opponents. Now it's hard to compare her to other juniors, because she didn't play many tournament in the juniors itf.