Simple scenario here - which one of these fine hypothetical gentlemen would you most like to have in your batting lineup?
Batsman A - Scores 40 runs every innings - if this guy bats a thousand times, he scores 40 a thousand times.
Batsmen B - Scores a century 4/10 times - for every ten times this gentleman bats, he scores 100 exactly four times, and gets ducks every other time.
Batsman C - Scores a double-century 2/10 times - for every ten times this man bats, he scores 200 exactly twice, and gets ducks on the other eight occasions.
Batsman D - Scores 400 once out of ten - for every ten times this bloke comes to the crease, he scores one score of 400, but gets a duck every other time.
Obviously a kind of silly hypothetical, but it has a semi-serious issue of batting consistency at its heart.