The chart is actually a stolen IQ (in this case, bar productivity) graph where the x-axis shows an increase in IQ (bar productivity) going to the right. The height on the y-axis only corresponds to literally the raw number of each IQ score (barista). So most of the scores are in the middle, and only a few scores are really low or really high. OP thinks that a small amount of the fastest baristas don't actually sequence (in the traditional way (I'd argue it's still sequencing, just a different kind)), but have a random bar style. Unfortunately that leaves us, who sequence the way they tell us to, in the middle when it comes to bar speed :(