The most straightforward way to solve this puzzle was to compute the probability distributions of the winners of each match recursively, given each swap. The most advantageous swap for the 2-seed is to swap seeds 3 and 16, which increases the 2-seed’s probability of winning by 6.55795%. One easy mistake to make was to accidentally report the 1-seed’s probability of winning after swapping the 2-seed with the 1-seed. This swap is good for the 2-seed, but only increases their probability of winning from 21.6040% to 23.0283%, so 1.4243%.

The following puzzlers managed to find the correct swap and the increase in probability.