Lovely bird, sharp and has a purposeful look. The light must have been harsh. I agree with your self crit, but I wonder if an EV >2 would have over-exposed the head? I haven't done it but I wonder if a bit of highlight/ shadows work would bring out some detail in the underside of the wings? I wouldn't have cropped quite as much, as for me the wing tips are a little close to the edge. Some slight rotation so that the wings form a true diagonal might also make it even more dramatic. These are minor points, and overall I like this image.
Nice points made my Richard. I believe you are probably right about needing +2 to get the darks correctly exposed but I also think with the harsh lighting that would have blown your head area as well. Maybe split the difference and recover what you can in pp?
I opened your image up and created a levels adjustment layer, sliding the midtones to the left (1.44) and that instantly brought out more detail in those underwings but it also created a huge amount of noise. You can always run NR but then you'll lose some of the detail in the feathers.
My guess is the harsh light is the problem here. If it were more overcast you'd have been able to produce a more even exposure. Let's see what the others have to say, though.