icanhit,
Everything that happens (workout and games) becomes part of the evaluation.
The top prospect game is played after all games have been completed. Players are selected after their last scheduled game based on the workout and the games.
While there are always players there that are highly ranked beforehand, every year there are many very talented players we see for the first time.
BTW, Top players standout at any event, no matter how many players attend. The two events are done more as a scheduling option for players.