the free agant's npub gets referenced in the 33401 when the task moves to "assigned" status. and when then task is concluded and the 3402 is created, the result of the job allows you to evaluate the free agent. so querying a whole set of events would allow you to evaluate the performance of all the workers involved. and future integration of WoT or GrapeRank would provide onlookers with their own tuneable algorithm for the various evaluations feasible to glean from the available data.