PHOENIX -- The D-backs reached their 40-man roster limit Friday by adding right-handers Jake Barrett and Matt Koch and outfielder Gabby Guerrero to the contingent, while designating right-hander Allen Webster for assignment.
Barrett, rated the organization's No. 18 prospect by MLB.com, finished a combined 4-3 with 15 saves and a 4.58 ERA in four seasons at Double-A and Triple-A. An Arizona State University product, Barrett is competing for Team USA in the Premier12 Championship in Japan.
Acquired from the Mets along with right-hander Miller Diaz in the Aug. 30 Addison Reed deal, Koch compiled a 5-8 mark wth a 3.20 ERA in 36 games (nine starts) at Double-A for both organizations.
Guerrero, Arizona's No. 14 prospect on MLB.com's list, was part of the four-player haul the D-backs received from Seattle in the June 3 Mark Trumbo deal. The nephew of former superstar Vladimir Guerrero, Gabby Guerrero entered Friday batting .300 with two home runs in 13 games for the Salt River Rafters in the Arizona Fall League. He hit .222 in 126 games for the Double-A affiliates with Seattle and Arizona after participating in the 2014 Futures Game at Minnesota.
Webster was 1-1 with a 5.81 ERA in nine games (five starts) for Arizona, in addition to posting a 4-6 mark and an 8.18 ERA in 15 starts for Triple-A Reno.
Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.