Surprisingly, I think it was written by a woman.
Actually if it was top five I would have listed Slap Shot and Let It Ride.
I believe both screenplays were written by Nancy Dowd, though Let it Ride was based on another author's book.
Seconded but my honorable mention goes to The SandlotHoosiers
Field of Dreams
Rocky
Yes, I looked it up and Slapshot was written by Nancy Dowd. It started out to be a documentary, but then changed into a fictional comedy. Her brother was a minor league hockey player.