  Much of modern society is founded on orchestrating institutions that produce
social goods by fostering motivated teams, pitting them against each other, and
distributing the fruits of the arms races that ensue. However, even when the
"market maker" is willing and able to maintain parity between teams, it may
fail to maintain a level playing field, as some teams acquire enough advantage
within the system to gain influence over it and institutionalize their
advantage. Using outcomes of over 60,000 games from four professional
basketball leagues and more than 100 years' worth of seasons, we compute the
evolving rate of transitivity violations (A>B, B>C, but C>A) to measure the
ability of leagues to maintain parity between teams, and support the efficient
generation and distribution of innovation. Comparing against a baseline of
randomly permuted outcomes, we find that basketball has become less competitive
over time, suggesting that teams diverge in performance, and reflecting a
possible failure of market makers to tame their overpowered teams. Our results
suggest that rich-get-richer dynamics are so pernicious that they can even
emerge under the watch of a powerful administrator that is motivated to prevent
them.
