First, the 28-year-old Tatum was put on waivers by the Orioles in early October, only to be claimed days later by the Houston Astros.
The Diamondbacks already have options at the catcher's position on their depth chart in the form of 2011 NL All-Star Miguel Montero and 14-year veteran Henry Blanco, with prospects Ed Easley, Rossmel Perez and Konrad Schmidt waiting in the wings, along with Ryan Budde, formerly of the Los Angeles Angels.
Tatum has had minor league success, having been named to two All-Star teams, but his major league performance has been limited.
Tatum played just 31 games for the Orioles in 2011, hitting .195 with zero home runs and seven RBI in 87 at-bats. In 2010, Tatum played a career-high 43 games for Baltimore, with a .281 batting average and nine RBI over 114 at-bats.
Tatum's only home run came during his rookie campaign with the Cincinnati Reds on Aug. 29, 2009, when Tatum took Dodgers pitcher Charlie Haeger deep in the midst of an 11-4 blowout at the hands of the Boys in Blue.
The move gives the Diamondbacks options in the event that Montero or Blanco get hurt and Schmidt or another prospect needs more time to develop at the Triple-A level, though Tatum is unlikely to play many games for the major league club.
Schmidt, who was named a minor league All-Star four times in 2010 and 2011, appeared in four games for the Arizona Diamondbacks in 2010, collecting one hit in eight big league at-bats for a .125 batting average.
Schmidt did have an MLB plate appearance in 2011.