For current players, they can address letters in care of the team. Van Buren Ave. You may be surprised to see how many athletes respond. You may also want to invite a local athlete, sportswriter, or TV sportscaster to visit the class. Many will come, and at no charge.
Baseball is particularly dependent on statistics.
Some students track them every day, and you can use stats to teach math. Challenge the students to find those towns on a map. See which state produces the most football players, basketball players, and so on. Pick a bunch of sports teams in different cities and have the students decide which team they'd like to play for, based solely on geography. They'll have to reseach each city.