4:58pm: Roberts has been told a trade is on the one yard line, MLB.com's Steve Gilbert reports (on Twitter).
4:39pm: The Diamondbacks announced that they designated Ryan Roberts for assignment. The move creates roster space for John McDonald, who's returning from the 15-day disabled list, and will spark trade talk involving Roberts.
The Tigers and Rays appear to have interest in Roberts, so Arizona GM Kevin Towers has at least two potential trade partners (the Tigers' interest was reported before they acquired Omar Infante; it may have faded since). Roberts, 31, has handled second and third for the Diamondbacks this year while posting a .250/.306/.357 batting line in 280 plate appearances. He earns $2.01MM in 2012 and will remain under team control through 2015.