The bullpen is the section of major league teams’ rosters that changes the most over the course of the year. A reliever could be replaced because of injury or ineffectiveness, just like at every other position, but sometimes he just gets sent down because his team could use a fresh arm. Kirby Yates didn’t look particularly bad to begin the year, but with the Rays’ relief corps getting a little strained, the team decided to replace him with Jose Dominguez.
Dominguez immediately gives the Rays better pure stuff than Yates, but it doesn’t come without a cost.