Sierra is primarily a shortstop but has shown the ability to also play third base. The 26-year-old was signed out of Venezuela by the Houston Astros in 2014. A couple years later he would be managed by RailCats current manager, Lamarr Rogers. Sierra made his way to Gary last year and starred in the last nine games. He finished with a .281 average, a .343 on-base percentage, and notched a hit in six of his last seven games. 

The infielder was traded to the RailCats from Sioux City and goes into his second season with the Cats and goes into his ninth season.