Thats hard for me to believe (mule deer vs whitetail) but I'd imagine you are more used to what you grew up on so I will claim cultural bias by the authors and guess they are from out west :0
Happy to see Elk in the #1 spot and never have had moose but hear its delicious, also surprised that antelope beat out whitetail and mule deer.
"Of course there were a few variables we couldn't control for...". That is huge understatement. The only way to accurately test this would have been to take each of those animals, make sure they are the same gender, same age, are raised in the same pen, kill and butcher them at the same time, use the same cut of meat, and prepared them exactly the same. I would not call this a very scientific test.
I much prefer deep woods Whitetails to agricultural whitetails. If the predominate diet is natural foods, they have a earthier flavor. Ag diet Whitetails are a bit more bland.
I guess I am really fortunate to hunt muleys that have access to winter wheat because I swear my mule deer taste better than the elk I harvest. My elk also taste awesome but damn the muleys are really fine! Now I tried my buddies muley from a different part of the state and I couldn't finish it and it did taste like ass.
They shoulda added blacktail to that list. I looove the way our coastal blackies eat. I might even like blacktail better than elk, though it's a tough, and I'm tasted lots of both from the same forests on the Oregon coast. Heck, I shot last year's spike elk 75 yards from where I harvested a big forky blacktail the year before.
I am not surprised that the speed goat scored well. I've had some very tasty speed goat before that fed on river bottom grass and alfalfa, though I hear it can be pretty rank if they only feed on sagebrush.
Personal preference the whitetail takes the edge over the mule deer. Surprised to see antelope up there. I don't mind speed goat but a lot of folks I know down right won't eat them.