That's a lot of drift between ~900-945 yards, 9" in 50 yards..
Even if the wind had been dead calm from 900 yards out to the target, it would still have drifted nearly 9 inches between 900 and 945 yards. The bullet travels a curved path in the wind, once it leaves the wind, it travels a straight path, but that straight path still diverges from the original path of the bullet.
It's like a bullet that got deflected one moa by hitting a twig right in front of the muzzle. The deflected bullet flies in a straight line but it misses the bullseye more and more the farther away the target is. One inch at 100 yards, two inches at 200 yard, 3 inches at 300 yards, etc, etc.