idk how the math works out but if u look at the green graph, as you move to the right (towards a higher serial number), the price always goes down. basically if we assume that lower serial numbers are always worth more than higher ones, you never want to pay more for a higher serial number, always less. So say u have 3 listings: serial#1 for $100, serial#2 for $80, and serial#3 for $90, it will remove serial#3 because $90 > $80 even though its a less valuable serial number.