Yes, I was weaing all the plastic armor as well. I fell pretty hard, the only thing that might have happened was that the plastic somehow missed my tailbone when I fell. They are great shorts, don't get ne wrong, and certainly better than most options out there. But I did manage to still bruise my tailbone pretty good with them.
And yes, I am 6'1", 210 lbs and in what I consider good shape. I run two miles a couple times a week. I also do a lot of core and upper body workouts and squats/lunges. And I do crossfit workouts a few days a week as well. So I don't think being shape is an issue for me, lol.
If anything other than my weight being an issue, perhaps the plastic guard moved before I hit.