Decio, I am amazed you didn't get more freeze from 1/2000th shutter speed; could be your focusing was off a bit instead. If this had been my image, I'd have left the rocks out and put the bird in the lower 1/3 of the image flying into the left side with way more room at the top. As is, he feels a little confined within the top edge of the frame.
Keep trying! Maybe bump up the ISO and get a little more DOF and SS and see how that works for you.
Hi Decio- These are very tough images to get right because the bird's movements are so fast. I agree the focus plain is on the log, probably where the bird originated, but has flown off the plain at the instant of capture. I think the 1/2000s should be enough to stop the action so the softness of the subject is caused by focus not movement.