This depends on what you were using as a target with which to test the lens's performance.
If you focussed, centrally, on a flat subject - say a flat board or wall with scribbles or something sharp like that on it, unless you could guarantee your camera was perfectly square to the target - easier thought than achieved in reality - your edges would go softer than the central area you focused on. And that could affect one side more than the other since depth of field doesn't work equally on both sides of the focussed distance. So, if your camera is slightly off the parallel with the target, one side will inevitable show more or less softness even though both extreme sides will be the same real distance in front of and behind the focus point, but the fact that depth of field isn't equal will make one look worse than the other.
Remember, too, that the wider the lens, the more that the sharp plane of focus resembles the form of a shell, and not a flat plane.
As for the Nikkor that was sent back - I can only repeat my own short-lived misadventure with the 24-70mm. And also repeat that I think it scandalous that such expensive stuff can be delivered without thorough, individual checking. There are no excuses that wash.