As far as predicting that a player labeled as injury prone would either get injured or stay injured doesn't really take much foresight IMO.
Personally I didn't have EJ as a top 5 SG mostly because of his injury problems.
Demps put himself in a position to act from weakness. Having to match a contract for a guy you consider a franchise player is an awful decision. The league has max contracts in place so the only way you can blow signing a franchise player is if he gets injured. Gordon is mentally weak which is ok, but as a GM if you are going to pay a player of that mindset you must cater to that player. These are all decisions Demps is paid millions to make.