This is actually incorrect. The numerator is BTC transaction volume and the denominator is BTC/USD exchange volume1. The sharp decline in the chart then makes sense, as we saw a massive increase in exchange volume over the past 4 months which is now decoupled from underlying bitcoin economic growth (people were speculating/anticipating future economic value).
Agreed that the blockchain Trade Volume vs Transaction Volume Ratio displays the ratio transaction volume / trade volume. I transposed the factors described in this
post. To check your constructive criticism, I ran the python script myself, and also inspected the most recent respective values from the two source charts: USD Exchange Trade Volume, and Estimated USD Transaction Volume. And I agree that as the bubble formed, the ratio decreased because of the relative increase of trade volume verses transaction volume.