Many of the players mentioned could be major contributors on the next contending Cubs team. That's one reason why. Another reason is because the firesale strategy usually fails. Bad teams that sell their good players for prospects tend to stay bad. The Cubs don't have many good players that will still be good when the Cubs are competitive again. Relievers are flighty enough, and someone like Marmol is a massive injury waiting to happen, so why hold on to him for 2-3 years of mediocre Cubs teams when teams who are in the hunt will be willing to pay big for a guy as effective as him even if it is just for immediate impact? Like it was pointed out, catchers don't have a terribly long shelf life, and Soto has already had injury and weight issues that are just going to pile up as he gets older. He's already near 30, so again, why keep him on for 2-3 years of mediocre Cubs baseball when someone with his skills will command a very good return for 3-4 years of being a very good offensive catcher he probably has in him? Why cling to someone like Byrd? Or Wells? Or Gorzelanny? Or Colvin?