There is often more to the problem than eyes & scope.

The caliber/load/recoil combination and the shooter's hold and ability to deal with recoil is also a factor. If the sighter was letting the gun drive straight back (sort of rolling with the punch) and the shooter was bracing for the recoil letting the muzzle jump it could account for the hits being high.

And as for eyes, I can sight a rifle with iron sights (not f/o) and my son's groups will be high/left of mine every time. I can sight one with a scope or f/o sights and his group will be much closer.
I can sight a "springer" air rifle with a scope and his groups will not be close to mine.

Eyes, the gun's sights and performance, the shooter's hold, and probably many other factors all enter into the equation!

It's always wise to check where YOU are hitting with the gun YOU are going to hunt with!