http://armyreservemarksman.info/2012/12/14/shooting-skill-snipers-vs-competition-shooters/

granted its apples and oranges but there is an interesting corollary. HP targets don't shoot back and the stresses are different.

It's also an entirely different standard of acceptable accuracy that the two groups are dealing with.  A competitive shooter thinks in tenths of inches, whereas a shot in the wheelhouse is a shot in the wheelhouse for a sniper.  Anything from belt buckle to forehead is a perfect shot for a sniper.  Being as the accuracy requirement is much looser for snipers, and that making the shot is only one item in a laundry list of job requirements that also includes things like, "Don't get killed", it's neither surprising nor disappointing that the results are what they are.