I forgot to mention this, but remember that Kyle takes the reading seated, which should result in a lower heart rate and therefore a presumably a higher HRV score (lower heart rate generally means more recovered, higher HRV score means more recovered).
Once you stand up your heart rate generally increases by 10 to 15 beats per minute, thus Kyle’s score may seem impressively high. I don’t think this matters much, as it is how your score fluctuates over time that really seems to help.
What you say about speed power athletes scoring poorly is interesting, as my most talented guy, who is a total speed creature, tends to score very poorly.
I’m interested in who Joel Jamieson credits in his book, as he is certainly not one of the leading lights in the HRV movement himself. He may have a decent working knowledge, but I presume he borrows heavily from others.