Its no different than height/weight metrics, hand size metrics, speed metrics, injury ratio metrics and win ratio metrics. Its a metric out there for evaluation, is does however show a lack of intellect and problem solving ability.
So if you have a QB that is on the left side of bell curve on nearly every metric data point what could one reasonably assume the results would be? In Tua's defense he is a functional QB in a tailor made offense when under optimal conditions. However as the metrics and performance on the field have shown when he that is not the case his performance degrades substantially to the point of being non viable. Probably a good reason why he isn't allowed to audible often, he needs a script. Does he read a defense well?, its still debated even on this forum and certainly within the media.
I know some of you want to point out other exceptional QB's with bad scores. However each QB on your lists have other attributes that well exceed the acceptable metric points. Example Dan Marino, every other metric was exceptional, Jim Kelly the same, Lamar Jackson the same, however even he up until the last couple of seasons was more a RB/QB than a QB. Jalen Hurts similar to Jackson.
Your average engineer can make a brick fly like an airplane, however does it make it a good airplane?