Castellanos, ranked as Detroit's No. 1 prospect by MLB.com, has slowed down this month with Double-A Erie after a stellar start to the season. In 25 games in August, he's hit .200 with four doubles, a home run and five RBIs. Castellanos is in the process of transitioning from third base to the outfield, and time in the fall league should provide him with more outfield experience.
Joining Castellanos in Mesa will be catcher James McCann, infielder Aaron Westlake and pitchers Tyler Clark, Matt Hoffman, Michael Morrison and Luke Putkonen.
The six-team Arizona Fall League is in its 20th anniversary season. The teams play in Cactus League stadiums, with the Solar Sox making their home at HoHoKam Park in Mesa, the Spring Training home of the Chicago Cubs.
The Solar Sox roster is made up of players from the Minor League systems of the Tigers, Astros, Cubs, Dodgers and Orioles. The season begins Oct. 9.