Ahmed, 24, finished fifth in the Pacific Coast League this season with a .312 average (127-for-407), including 26 doubles, 4 homers and 47 RBI in 104 games with Reno. He also appeared in 19 games with the D-backs from June 29-Aug. 7, batting .228 (13-for-57) with 2 doubles, 1 homer and 4 RBI. He entered the season as the D-backs' No. 11 prospect by MLB.com, and won the 2013 Minor League Rawlings Gold Glove Award as the top defensive shortstop. In 4 Minor League seasons in the Atlanta Braves (2011-12) and D-backs' (2013-) organizations, Ahmed has batted .269 (443-for-1648) with 96 doubles, 18 homers and 166 RBI in 429 games.
Chafin, 24, combined to go 9-7 with a 4.08 ERA (67 ER in 147.2 IP) in 26 games (25 starts) between Double-A Mobile and Reno in 2014. In 2 playoff starts with the Aces, he combined to throw 15.0 scoreless innings, including a 4-hit shutout on Sept. 4 @ Las Vegas. Chafin, who made his Major League debut with Arizona on August 13 @ Indians with 5.0 scoreless innings, is 28-21 with a 3.99 ERA (190 ER in 428.1 IP) in 84 games (75 starts) in 4 Minor League seasons in the D-backs' system.
Wilson, 31, has appeared in 76 games with Reno this season, batting .267 (72-for-270) with 11 doubles, 3 home runs and 38 RBI. He was signed by the D-backs as a Minor League free agent on Nov. 24, 2013. In 5 seasons with the Angels from 2008-12, Wilson hit .208 (81-for-389) with 8 home runs and 37 RBI in 191 games. He last appeared in the Majors with the Los Angeles Angels on Oct. 3, 2012 @ Mariners. Wilson will wear No. 18.
To make room on the 40-man roster for Wilson, the D-backs transferred right-handed pitcher Bronson Arroyo (Tommy John surgery) to the 60-day disabled list. The D-backs' active roster is now at 35. The 40-man roster remains at 40.