To access a players contract discussion/thread you must go to the Contract Signings page and click the small blue icon next to their name. This is the only way to access these threads, at least that I know of. It would be nice to have access to the contract discussion threads on the individual player page next to the contracts that are on the player pages.

This could make it easier to view a player's contract discussion who has had several contracts across multiple teams. The current signings page is not necessarily friendly when trying to do this. Maybe a search function on the signings page could beneficial as well.