Why would the Sox put Duran on the bench? If he comes up, it's to start.
Kimbrel is having a great year, but I seriously doubt the Sox give up Jeter Downs for him. Kimbrel is also expensive, which, unless the Cubs pay a huge chunk of money, drastically reduces what they get in a trade. BTV gives Kimbrel a trade value of 0, which feels a bit low but by the deadline he will still have owed about $6.3 mill (with a $16mill option for 2022). BTV gives Downs a surplus value of 29.6. So even if the Kimbrel value is low, like I think it is, Downs is still a massive overpayment. Maybe someone like Jay Groome (BTV value: 4.3) would be the best offer the Sox make....