I've seen it happen a few times. I myself kind of did the same thing. Every day I regret not trying harder to play. I had to switch schools in 6th grades before Middle School tryouts, but when I got to my new school their tryouts had already taken place so I was out of luck. The next year same thing when I switched back, (then switched again.). Along came 8th grade when I was badly burned and was out of school 3/4ths of the year. After that I never tried to make the team in highschool because I figured I wouldn't make it having not played as much as I should have. I was told to try out by my parents, friends on the team and hell even the coach himself but I still thought I didn't have a chance considering the length of a break I was forced to take from playing.
If he doesn't continue playing I hope he doesn't regret as I do. Now I just wish there was some sort of league I could play now.. I was really good, still am after I warm up a little but I just really want to play. No leagues out there besides College ball for a 19 year old.
I'm not sure what to tell you to tell him other then if he doesn't there is a good chance if he likes the game at all he will regret it. Video games are fun but nothing beats running around those bases with a crowd cheering you on.
Good luck man I really hope he doesn't quit, and I hope this helps a little.