All fair questions. I looked at two large units I'm familiar with. One in a very remote area and one adjacent to a very populated and hard-hunted area. One thing these graphs leave off is "hunter success rate". I looked at "General Season" hunts from 2007 to 2012 where number of available tags is not a factor. It appears that hunter numbers have significantly fallen off. In the populated unit, they dropped by about 24% and in the remote unit they fell off by about 48% (not many hunters in this area anyway). As you can see, there are far fewer hunters in the field. Generally, one would think if there are less hunters and the same amount of game, the success rate would be good or better than before but by my estimation, hunter success in the remote area fell off by 29%ish and in the populated area, by 28%ish (a uniform drop off).
How to interpret this? Who knows? Until they start tying up elk in malls, unless single parent homes (moms) teach their kids to hunt and the existing hunters figure how to turn back the clock, hunter numbers will take a hit. I think deer and elk numbers have taken a hit too. The success rate suggests this and just poking around in the woods, I see less sign. It could be environmental, biological or predators. I did notice that mule deer numbers in the West were crashing before the wolf problem so I don't blame the wolves entirely but they're definitely part of the mix. I noticed that the take-numbers and the success-rate appear to be leveling off. We should see predation diminish as food supply diminishes and disease takes over.
My take... If you can afford it, buy a guided hunt where the success rate is high. If you can't afford it, do more pre-season scouting. If you can't do that, just go hunting anyway and forget things like success-rate because even when the odds are good, they're still against you but at least your hunting.