Having more quality arms would be great. But if you don’t have them, you have to work with what you have.
I’ve been plugging the idea of using your best arm for high leverage over straight up closer for several years now, and I think it’s really cool to see several teams adopt this philosophy. My one caveat is I do think the sixth might be a tad early to bring in the high leverage pitcher, but only because those dreaded opposing best hitters still are guaranteed another plate appearance. But then we all saw Francona bring in Miller in the ALDS a couple years ago that early and it worked out just fine...