SJL:
Outside of the Columbus Whalers organization it is hard to think of a more promising young pitcher in the SJL than Seattle's Steve Rosales. What is particularly impressive about Rosales is how well he is pitching given that according to most scouts he is probably not even half-way developed towards his full potential, which if it comes to pass should make him a strong candidate for several Pitcher of the Year awards in the future. (With apologies to Houston's Jack Hettinger, who also looks like a budding future star, in spite of his continued struggles with control.)
MGL:
David Freeman, plucked out of an independent league ball by Charlotte this past March, has been a revelation this season. With his elite speed and defensive skills he has taken over as the starting right fielder for the Sting and leads the team's position players in WAR at 3.0. Although he doesn't have a great reputation as a team player (Personality class: Selfish) if he keeps playing like this it won't be a big issue. And he's only 22 years old!