Its clear by the number of injuries and lethargic play that something is happening to the Nuggets this season. My theory is that basically their bodies are breaking down because it can't handle the strain of their tempo night after night.
As a past nearly elite-level long-distace runner, during my training I can recall a similar issue happen to me. When I continually did maximum training for long periods (4 to 6 months of varied runs of 50 to 80 mile/week), eventually my body would shut down at certain points as it couldn't produce enough reserves to keep up with the energy and vitamin requirements it needed to sustain that level. Usually this would happen after 4 to 6 months of serious training, at which point, my overall performance would decrease or be flat for quite a time (four to six weeks). I would find that after I overcame these lags, my body would eventually recalibrate my energy requirements, and began to modify its physiology to allow me to use and expend energy more efficiently than before. This would eventually lead to a sudden and unexpected surge in performance that would allow me to push my performance for 3 to 4 month. Then I'd stay at this higher plateau for about a year, before hitting another lull. I recall these cycles happening about five times over the course of 8 years.
I think this is likely the problem Karl is having now pushing his team to keep up the torrid pace, both on offense and defense, which is not sustainable, especially given the concentrated training cycles. My assumption is that the team is at a critical juncture in terms of performance, given their style of play, and may have peaked for this period. Perhaps in about four weeks, their bodies will have adapted to their current workload and they can have a surge in performance that can carry them for the season. My assumption is that if they kept their core team intact, with a lighter schedule next year, they could probably produce better results that could carry on for the whole year.
My biggest concern is Lawson, who I'm not sure can continue at the same pace indefinitely, without a severe physical letdown. I notice that he is definitely not the same player on back to backs as during the initial night. I think its important that we recognize that players are humans (albeit very talented) and plan accordingly.