There is no real right way to go about constructing a big league bullpen, but the SF Giants have a model of success that president of baseball operations Buster Posey seems to be trying to replicate and it was a model used by his predecessor.
Back in 2021, the Giants had a miraculous season thanks in large part to their solid bullpen. Farhan Zaidi pieced the relief corps together with minor signings and it worked out brilliantly as the team won 107 games.
SF Giants trying to replicate 2021 bullpen strategy
That amazing season featured unheralded relief arms like Dominic Leone, who recently talked about that magical run, Jake McGee, Jarlín Garcia, José Álvarez, and Zack Littell.