Not that I’m arguing for it, you understand, but the reasons one might choose to deal Swagerty for Bell are
a) we’re in a contending year and the 1-2 wins Bell might add over the rest of the way are highly valuable in a likely very close NLC finish.
b) and more importantly, IF (as I said) Bell is a type A and the compensation set-up in MLB remains much the same, he will net us 1 or 2 high draft picks in the next year’s draft, which are likely worth as much as or more than Swagerty, a guy who I really like and who’s had fine results so far but who likely isn’t going to be more than a back-of-the-rotation starter or set-up guy in the majors.

The Padres likely wouldn’t accept Swagerty for Bell anyway; they can simply keep him and gain a couple of draft picks next year, which i expect they’ll do if they don’t get a better offer than a low-to-mid-ceiling, high-A starter.

FWIW I agree with your point that a closer isn’t really required, but it’s unarguable that Bell would improve our bullpen greatly (I can’t see Sanchez back, and really, with the possible exception of Salas, none of the other guys in that pen likely have late-inning roles on many contending teams. It’s a weak pen, and if we make the playoffs, I really think our poor pitching in the rotation & bullpen makes us a rank outsider). Personally, I’d rather pick up a left-handed reliever, because Miller and Tallet both royally suck, but if the asking price for Bell is as little as Jordan Swagerty,