What we're trying to "overanalyze", Kev, is why we've seen three straight backup goalies come to Carolina and watched their save percentages all drop 20 points under their career SV%, even as Cam manages to stay miraculously at .910 or so. And here are the possible answers:
1. Small sample sizes reverting (repeatedly) to the mean.
2. Something in the Canes style of play is better for Cam and worse for literally everyone else.
3. Something in the Canes style of play is bad for all goalies, and Cam is way better than we realize.
After years of this, I am actually starting to lean towards 3. I wonder if Cam is a career .925 goalie stuck behind a legendarily terrible team.
I think it's clearly 1. There's no guarantee that a backup -- even a backup with lights-out stats -- will succeed as a starter. As a matter of fact, I'd be willing to bet (without doing any actual research) that most backups fail in the starter's role, but the ones who succeed (Talbot, Jones, Schneider) are bigger stories, so more people remember.
Plus, trading away great goalies is bad asset management. If the Blackhawks thought Darling had the goods to be a top-15 starter in the league, they wouldn't have traded him for a third-rounder, even if they were in a bit of a goalie pickle. Teams are going to find a way to keep the more talented guy. The Lightning found a way to keep Vasilevskiy, for instance. Lundqvist has survived about 10 solid backups, some of whom have had success elsewhere, some of whom didn't.
So at the end of the day, I'm not sure if backup diving is a great plan. It sure doesn't seem so after the past 12 seasons, since the last time we actually developed our own goalie. We're going to either have to develop another one, or pay up to acquire a top guy in trade. Another game of backup roulette won't sit well with anyone.