Straw That Broke the Camel’s Back

We've seen cases in wrestling where a career ending injury was caused (or it started a problem) by a singular move gone wrong, and also the ones where an ongoing problem was eventually capped by a bad move & the career went downhill afterwards.

The recent thing with Paige appearing to be at the end of her career due to a basic kick sounds more like the latter, which was just the final straw on a bad neck. It got me wondering about other cases, specifically HBK.

Was Shawn's back f**ked for that whole period & the Casket Match backdrop was the final straw, or was he physically okay & the backdrop caused it?
From what I believe Shawn has said in the past, the casket was basically the one bump that incited neck problems that were there the whole time.  If it wasn't that, it would have been something else that cashed in his bump card.