Elmore has played all over the diamond the past two seasons with the Diamondbacks in 2012 and Astros in 2013, seeing most of his time at shortstop and second base but also playing all three outfield positions, first base, third base, catcher and even pitched an inning. It should be noted that the last two positions came in one game when the Astros' back-up catcher was injured and regular catcher Jason Castro was DHing and he then moved to the mound when the game went to extras.
His career line is .233/.290/.298 in 209 plate appearances. He's got decent plate discipline, taking some walks and not striking out much, but the 26-year-old doesn't have much power. He's got a weak arm and doesn't seem particularly rangy. The righty has been well below replacement level. Looks to be simply a depth move.
It is notable that Elmore played in the Diamonbacks organization, as Buddy Bell's son, Mike, is their farm director. He does talk a good game regarding OBP:
The ability to get on base is a key to my success as a player and being disciplined at the plate is the key to obp. Over time I hope to maintain this ratio [1:1 strikeout to walk] because I do think it is important. Although, I would sacrifice a few strikeouts for a few more home runs in a season.
All three of these players will now be protected from next month's Rule 5 Draft. The 40-man roster is at 39. These are likely to be the last moves prior to the midnight eastern deadline to add players but you never know.