Is a threshold at 70% of target defensible when half the team falls below it?

The rule of thumb I was taught and still use is that around 90% of sellers should reach threshold, 55% to 65% should reach target, and 10% or so should reach the top tier. Half the team below threshold means either the targets are too high by a wide margin or you have a hiring problem, and with 44 people it is unlikely to be hiring.

I would show management the distribution of targets against each producer's prior three-year average. If most targets are 40% above anything the producer has ever done, the argument makes itself.