Jokes aside, IMO, how long this can last is going to be a measure of how well this bullpen can hold up.
You're right, by now it's usually taxed and worn out. I'm too lazy to check the numbers but I do believe our starters, while not spectacular, have been giving us slightly more and better innings this year than they have in the previous year or two.
The coaching staff deserves some of the credit, but Elias does, too. Betting on a guy like Cionel Perez and trying to determine if he'd be receptive to the coaching is a lot of work. It's a team effort for sure and, IMO, not any one specific party should get the majority of the credit.