Ross, 33, has appeared in 66 games with Arizona this season, batting .238 (38-for-160) with 5 doubles, 2 home runs and 11 RBI. In 25 games prior to being placed on the disabled list on July 22, he batted .358 (19-for-53) with 3 doubles, a home run and 4 RBI.
Hudson, 27, began the season on the disabled list while recovering from his second Tommy John surgery on June 18, 2013. He made 6 rehabilitation starts with Triple-A Reno and Rookie AZL D-backs and posted a 1.50 ERA (1 ER in 6.0 IP). Hudson last appeared with the D-backs in 2012, going 3-2 in 9 starts before suffering his first torn ulnar collateral ligament in his right elbow on June 26, 2012 at Braves.
The D-backs active roster is at 27 and 40-man roster is now at 40.
It looks like that will be the extent of the Diamondbacks' roster expansion at this point: given their position in the standings, in contrast to the playoff positions for both Triple-A Reno and Double-A Mobile, this isn't much of a surprise. Given the length of time he has been away, it's the return of Daniel Hudson which I am delighted to see. It has easily been more than two years since he graced a major-league roster: it'd be funny if he hadn't shaved in that time or something. Just a bit of a shame it looks like his return won't happen in front of a home crowd, where I'm sure he'd get a deservedly warm welcome.