Good science always leaves the door open to alternative explanations, even when it may be unlikely. In this case the researchers were relying on BMI to measure obesity. BMI doesn't account for musculature. To not even consider this possibility would be the domain of agenda-driven research, which this paper clearly was not.

Here is a link to the actual paper [1]. Their concluding statement was:

"Professional athletes are not immune from the growing obesity crisis and may not provide optimal role models of health. Concussions have drawn attention to overlooked long-term health consequences of sport participation. Increasing body mass in professional baseball players warrants similar attention for its potential impact on long-term morbidity and mortality because these players hold a special place as role models of health and human performance in our society."

[1] - https://sci-hub.se/10.1016/j.orcp.2016.09.003

Spot on. BMI is a bad indicator of individual health and fitness. I have a BMI of 25 right now but that’s because I added 14lbs of muscle over the last year while dropping a couple pounds of fat. Body fat percentage sitting at 18%.

Now, there are lots of big boys in the NFL that definitely have a couple extra pounds on them, which could also be skewing numbers.