I highly recommend the Roy Tucker/Brooklyn Dodgers series by John R. Tunis, beginning with
The Kid from Tomkinsville. These were written in the 1940s and are ostensibly young adult books, but quite enjoyable and still interesting and thought-provoking. They have been published digitally by Open Road.
Also:
- The Natural by Bernard Malamud
- Shoeless Joe (basis of the film Field of Dreams) and The Iowa Baseball Confederacy by William Kinsella
- The Southpaw, Bang the Drum Slowly, and Ticket for a Seamstitch by Mark Harris
For nonfiction:
- The Summer Game and anything else by Roger Angell
- Eight Men Out by Eliot Asinof
- Boys of Summer by Roger Kahn
- Why Time Begins on Opening Day by Thomas Boswell