In plain English
Miners must sell some new coins to pay bills. Puell compares today’s miner dollar revenue to its average over the past year.
Very low (green, under 0.5) means miners are earning a lot less than last year’s typical day — historically nearer to stress and good long-term buys. Very high (red, over 4) means issuance is lucrative. After a halving the number drops overnight because the subsidy was cut while the year-long average still remembers the old subsidy.