I don't doubt Eovaldi would be good as a set up man, but guess what? The Sox already have Ottavino, Whitlock, and, last night (when he gave up 2 dingers during a downpour at Yankee Stadium) notwithstanding, Sawamura. Plus Houck, I would think.
Meanwhile, the rotation suffers because, unlike the relievers, they have to go through opposing lineups at least twice and often three times. So, me, I would give the rotation priority over the bullpen, especially because it's already pretty good. So, come August, my rotation would be, in order, Sale, Eovaldi, Pivetta, ERod, and Perez. And, because those 5 include 3 lefty starters, I just might stretch Houck and start him over Perez. As for Richards, I'd give him Andriese's old slot.