Listed at 6 feet 0 inches (1.83 m) and 215 pounds (98 kg), Castillo throws right-handed and is a switch hitter.

In 2008, Castillo was named the 14th-best prospect in the Diamondbacks organization,[1] and played 104 games in Triple-A for the Tucson Sidewinders of the Pacific Coast League, batting .254 with six home runs and 47 RBI.

On September 1, he was called up and made his MLB debut the following day against the Pittsburgh Pirates, flying out to left in his one at-bat as a pinch hitter.

He began the 2009 season with the Triple-A Louisville Bats after failing to earn a spot on the Reds' roster.

[3] On November 30, 2010, Castillo signed a minor league contract, that included an invitation to spring training, with the Atlanta Braves.

[4] He spent the 2011 season with the Triple-A Gwinnett Braves, recording a slash line of .262/.285/.366 with five HR and 37 RBI in 80 games.

[8] On February 26, 2016, Castillo signed a minor league contract with the Toronto Blue Jays organization.

In 51 games split between the Double–A New Hampshire Fisher Cats and Triple–A Buffalo Bisons, he batted a combined .229/.271/.312 with one home run, 12 RBI, and two stolen bases.

[10] He played in 59 games split between the Double–A Trenton Thunder and Triple–A Scranton/Wilkes-Barre RailRiders, accumulating a .196/.243/.286 batting line with three home runs and 13 RBI.

[11] On March 27, 2018, Castillo signed with the Long Island Ducks of the independent Atlantic League of Professional Baseball.