I know Caba's ceiling could be high (and his floor still good as well) but I find it kind of hard to lament the loss of a 19 year-old whose OPS was below .500 in low A (admittedly in late/limited action). Anytime you can trade someone who is that far away (as opposed to Crawford, or O'Hoppe for that matter) it's not a bad thing for a team in the Phillies position.
Still don't understand why everyone thinks they need another reliever, or where he'd slot?
Romano
Strahm
Kerkering
Alvarado
Ruiz
Banks
optional # 7 spot (Lazar)
long/swingman (Walker and like five other candidates)
This team's success has pretty consistently been with less heralded relievers, whether a total dumpster dive like Hoffman or a journeyman like Strahm. As opposed to Kimbrel (who was decent but not elite) or Estevez (ditto) or Knebel or Soto (an All-Star close). And don't even think about the 2020 team. It's just too bad there doesn't seem to be another Kerkering or Seranthony in the wings, though there still could be.
The coaching staff also deserves a lot of credit for how they've tutored and utilized both the relievers and less heralded starters (just not Walker or all those other guys last year alas).