The only guys dealt away who qualify as 'under control' are Weaver (one year) and Brazoban (three more). With both I suspect their justification is:
a) selling high. Relievers are notoriously tough to rely on from year to year. And while Brazzy's resume is unusually short for a 36 y/o, this was, by far, the best year of his career. ERA ('22 - '25): 3.73; ERA in '26: 2.56; WHIP ('22-'25): 1.33; WHIP in '26: 1.006 ... And I KNOW few if any of you/us or NYM fans in general, were sayin 'Oh good, it's Brazoban coming in form the pen' prior to this season.
b) he'll be 37 y/o next season
Weaver is younger and even better but rewind all the way back to 2023 and you'll see Luke Weaver traded twice in season due at least in part to the 6.40 ERA and 1.58 WHIP he pitched to that year. So the 'selling high' and unpredictability things again.
Raley, Taylor, Holmes (player option), Peralta were all free to leave in seven weeks time.