Tar Heel:
I have been a professional photographer for 40 Years. I have worked many sporting events where "LONG GLASS" was involved. I know how much an SLR with a 400mm lens can weigh. Most of the time lens of this focal length are supported by a monopod but occasionally when moving in for what you think a great shot adrenal glands take over and you find yourself supporting the camera, lens, and monpod with your neck. This is probably the root of your problem. I have several aftermarket straps for different cameras, some very wide and very long. When assigned to a sporting event, rare for me nowdays, because I cannot move as briskly as I once moved, my age... I wear the strap attached to camera across my left shoulder and under my right arm, this transfers the weight to shoulder instead of neck.. Non professionals would say why strap at all, use the monopod.. BUT, you and I know that long glass is expensive and with humpten other photographers all competing for the same photos a bumps and shoves coming from all directions, a damaged 400 f:2.8, $14,000.00 lens can ruin your day.
darrell