The Mariners would have little interest in Jarren Duran, a poor man's Taylor Trammell, the defensively adept Seattle center fielder who is a year younger than Duran.
A very poor man.
In 58 games year Duran posted a negative 0.4 fWAR and 78 wRC+ while in 44 games Trammell posted a positive 0.4 fWAR and 99 wRC+.
On the Seattle outfield depth chart, Duran would likely fall behind Cade Marlowe, who is on the postseason taxi squad despite never have played an MLB game.
This season Marlowe, who is 10 months younger than Duran, posted a .287/.377/.487/.864 with 23 home runs, 102 RBI and 42 stolen bases between Double A and Triple A. Nevertheless Marlowe may be a Rule 5 casualty:
https://blogs.fangraphs.com/examining-the-american-leagues-2022-40-man-crunch/
BTW in the trade for Luis Castillo the Mariners traded away two "Must-Add Prospects" from that FanGraphs July analysis of American League 40-man roster crunches.