Well, first of all, another team having to deal with his sub-par post-ASB hitting is not our concern.
Secondly, despite his other flaws, power like Mark's does not grow on trees, especially in a supposedly post-PED's era. Trumbo is consistently putting up 30+ HR seasons along with a steady 2+ WAR per season.
That has value, especially considering that Mark is entering arbitration for the first time. I know many of you look at what he would bring back in terms of Major League players but the reality is that Mark would bring back a significant pitching prospect (think Archie Bradley for instance) plus another prospect or two.
Our greatest haul will come through prospects, not other MLB players. Although there is always inherent risk with acquiring prospects, their long term value and cost-control is what will help turn this team around in future years.