I would say that you are describing my team except I don't think that our HS program has EVER had a season over .100.
I served as a dad assistant for a year and a half and 1/3 through the season last year the head coach basically just gave up so I took the team over unofficially of course because I was not qualified through TSSAA. The Director of Schools of our School District approached me and asked me to take the team over and build the program. I did all the NFHS courses and got my certifications to be the Varsity HC. I committed to them for 2 years since my son graduates 2019, I may hang one more year depending just because my team is heavily populated with 2020's.
This team has not won a game in at least 5 years, meaning my seniors have never tasted victory. Here's what I have done...
First and foremost, scheduling, scheduling, scheduling!!! I went through MaxPreps and looked at teams all around me to see what I could put on the schedule for non-district games. We opened the season 3-0. Matter of a fact, when we played our first district game there were 4 teams in AA Baseball in the State of TN that were undefeated...we were one of them. Now, we played 2 teams that were absolutely awful, but one of the wins was a legit win that we came back from an 6-0 lead to win 9-6 scoring 6 runs in the 6th inning to win the game at home. This did the absolute best for building some confidence in our program as well as some excitement in the school and county.
Just shy of scheduling is RECRUITING!!! I serve as the Chaplin for the football team as well as am very involved in mentoring some of the basketball players. When I say recruiting, I don't mean out of district, I mean in the halls. The last football game I bought a cooler of water and individual drink packs and after the game every player lined up to come get a drink and told them great season and asked if they played baseball. I had a preseason meeting with my returning players and told them to find the athletes or those that are hiding in the halls that have played baseball and get them to the field during preseason workouts and when the season opened for tryouts.
From there, it's really just fundamentals, fundamentals, fundamentals. Invest in a summer pitching camp. If you can't afford to send them find some travel ball coaches to come do one for you at your school (check your State guidelines).
Stay positive! I think baseball is a gentlemen game and although there are times when they may need a good butt chewing (last night for my team) remember that baseball is a mental sport and that not being mentally aware in the game produces errors and errors produce more errors.
As far as your son is concerned, the comments above are perfect in that he has the opportunity to showcase himself at every at bat and every pitch.