I find it almost impossible to get a passerine in flight. They are so fast and unpredictable. Every picture I ahve of a small bird in flight is quite horrible. There is something that always can go wrong. I had a scarlet tanager as you can see below, perfectly in focus off the branch... too bad i was on the worst possible shutter speed making the red bird look black.
The parairie warbler is just bad
Swallow out of frame