Those are pretty soft, however I think the issue isn't so much the lens as a front focusing issue. In all the owl shots, I can see the grass in front being in focus more than the owls. Not sure if you have any other bodies that might allow focus adjustments, but if so, I would try that lens on those bodies.
The owls photo was taken on a Canon EOS 400D (which I no longer use) the others on my Canon 7D MK II. How do I change it on my 7D MK II?
Is this a good advice to follow?
(Sadly my garden is not 25 meters long so I will have to go to the park)
Although saying that I know someone who uses the 400D and might use my tamron with so any advice would be useful.