Congrats. You are doing the right thing getting him to events where he can be seen and by performing well will get him noticed.
PG rankings, in general, come from attending their showcase events where players are evaluated and get a specific PG rank. Does it help? Yes. Is it necessary? No. It all comes down to time and budget, Players at the high end of their scale get invited to their invitation only events which are very helpful.
Good Luck.