Well, like any other actor Chloë has her forces and her weaknesses. She's clearly the strongest when playing the silent, melancholic type (fx. Let Me In) or the action, tough girl type (Fx. Hit-Girl - not Mindy), but she also got the great skills at playing crazy (Clouds, Dark places) and cute (Fx. Laggies)
But yeah, I'll agree that playing normal, or naturalistic as you say, seems to be one of her weaker spots.
But it's hard to improve if you don't try roles that challenges your weaker points. And Chloë's been doing a lot of different types of roles, so naturally some will be hits and other misses in regards to her acting skills.
But maybe, as you say, that is what she is assessing and what she means by being more picky (I wish we knew more what the hell she means sometimes, so we don't always have to speculate). Maybe now is the time where she'll go: Okay, I've done this and that worked great. I've done that and it didn't work out so great. So maybe I should focus on the aspects where I'm best.
Chloë just needs to go back to the type of roles and characters that suits her acting skills the best (and of course also suits what she wants to portray). More silent sadness or more action tough, snarky roles.