Jose Rafael "Jumbo" Diaz[1] (born February 27, 1984) is a Dominican former professional baseball relief pitcher.

He played in Major League Baseball (MLB) for the Cincinnati Reds and Tampa Bay Rays.

Diaz is nicknamed "Jumbo" for his large size; MLB.com lists him at 6 feet 4 inches (1.93 m) and 315 pounds (143 kg).

Díaz pitched in the Cincinnati Reds system in 2013, going 3–4 with 13 saves and a 1.66 ERA for the Louisville Bats[2] – he had a 1.03 WHIP and struck out 60 in 54.1 innings.

[11] On July 31, 2017, Díaz signed a minor league contract with the Houston Astros organization.

[12] In 12 games for the Triple–A Fresno Grizzlies, Díaz posted a 2.92 ERA with 11 strikeouts and 3 saves in 12+1⁄3 innings pitched.

In 38 appearances split between the rookie–level Gulf Coast League Marlins and Triple–A New Orleans Baby Cakes, he accumulated a 6–6 record and 2.18 ERA with 52 strikeouts and 12 saves.

[1] After the 2020 season, Díaz played for Águilas Cibaeñas of the Dominican Professional Baseball League (LIDOM).