Arizona lost its shortstop, Stephen Drew, to a nasty injury last month, but opted not to pursue outside alternatives and instead use utility man Willie Bloomquist as the regular shortstop. Bloomquist, 33, has actually been a decent stop-gap for the Diamondbacks, posting a .280/.341/.402 line in 20 games since Drew landed on the disabled list.
But Bloomquist is likely being stretched as a regular at shortstop given his iffy defense and poor hitting track record, so it's not surprising that the Diamondbacks are interested in alternatives. The Reds are essentially out of contention with the Brewers up 12 games on them, but they may be willing to deal Renteria anyways with the younger Paul Janish around for the rest of the season.
Renteria, 36, may no longer be a quality regular option at shortstop, but he would give Arizona another decent option to join Bloomquist, and some executives in that organization likely have his performance from last year's playoffs on their minds as well.