ZD: The first answer you selected was to have your son on a rec team with a great coach rather than a travel team with a mediocre coach. This, in my opinion, was a wise choice since good coaching is more important than playing lots of games for player development.
You then chose to have your son play on a team that practiced rather than just playing games. Again, a wise decision because practice with lots of reps is where you learn. How many ground balls will be fielded by an F6 in an average game? Maybe 4 or 5? Same goes for reps with batting technique and working on defensive situations. A player learns in practice and uses what he has learned in games.
Your son, on the other hand, chose to play and start on the freshman team which generally is a short season with too many dead wood players. While he would have played less with the varsity team the practices would have been much more educational and challenging. As far as development goes sitting the bench with the varsity in games is trumped by practicing with varsity against tougher pitching and overall stiffer competition.
For most players being assigned to the frosh is a death knell. Excel there or flip burgers next season. Quality frosh are on JV and given the opportunity, and rejecting it, to be nurtured by the varsity coach also sends the wrong message about how serious a player is. This is the age to be the best you can be and get an edge for the next season, it now a sprint to excellence ahead of your peers. There is plenty of time to be had playing summer ball and having been a varsity player gives a player some clout.