You're not wrong, but a team like the Rays very much does this kind of thing. Fairbanks, Nick Anderson, Jalen Beeks (part of their current pen) were all traded for very tangible assets. They traded Willy Adames, the centerpiece of the Price deal, for J.P. Feyereisen (sucked, now good with the Dodgers), Drew Rasmussen - originally a reliever, good but broke under a starter's workload, and our very own Trevor Richards went to the Brewers, acquired via previous trade. It's just really f***ing hard to build a good bullpen, the elite arms are worth a fortune, the half capable ones cost real players (Teoscar, Groshans), and the rest of them are a bunch of gas cans.