Average is the mean (i.e. sum of all "skill" divided by the amount of programmers)

What they were thinking of is the median (50th percentile = 0.5 quantile), which splits the group in two equal sized groups.

For a bell curve, they are the same values. But think of the example of average incomes: 9 people have an income of 10$, one has an income of 910$. The average income is 100$ ((10*9+910)/10). The median is basically 10 however.