I shot this in YNP. It was the first time I have seen, much less photographed, a cassins finch. I was sitting on the ground & he allowed me to get quite close to him.
Mark IV, HH, FF, ISO 400, f/5.6, 1/640, +0.67 ev, 100-400@400
Andrew, Sharpness is good. The main issue is that the shooting angle has resulted in a BG that is not very attractive. Not sure if you could have gone lower. That usually helps in getting good BG. Looks like your view would have been obstructed by the vegetation.