With the unfortunate attack by the first base line yesterday, Cody Ross will be done for the year. His being added to the disabled list, although apparently not yet official, will free up a roster spot for someone else. What piece of the future will we see next? It partially depends on whether or not Ross is placed on the 15 day DL or the 60 day DL. Here is my list of the candidates, from most likely to the more unlikely.
Alfredo Marte: he didn't do well in limited action with the D-backs early in the year, and hasn't exactly lit up the PCL either. But I just don't see the D-backs going with Jason Kubel as the only backup outfielder for any period of time, and Campana has gotten a look more recently. But while I think he's the most likely, his lack of pop this year should be worrisome; he hit 20 home runs in Mobile in 2012, but has only managed 3 this season in Reno. The fact that he is already on the 40 man roster is pretty much the biggest thing in his favor.
Tony Campana: as with Marte, the biggest thing in his favor is that he is on the 40 man roster. He's also a better fielder than Marte, which would make him a better fit as a defensive replacement (which is probably all that the replacement will be). But I don't know that the D-backs would want to burn another one of his options, and he doesn't really bring anything to the table the D-backs don't really have. It's basically a toss up between Marte and Campana, but I think the number of options is the tie breaker.
Josh Wilson: he's not on the 40 man roster right now, so this spot (and those below) would be only in the event of Ross being placed on the 60 day DL (and it will probably be a day or two before that happens, if that happens). KT/Gibby could decide to turn Prado into an outfielder full-time, and then Wilson would be a logical defensive replacement. The only possible issue is that Prado, with Chavez on the DL, is the backup first baseman, but Wilson does have four career games at first. That, and the fact that he wouldn't be taking away playing time from anyone else, makes Wilson a more attractive option to me than Chris Owings.
Justin Greene: Greene isn't exactly a top prospect (and might not really be a prospect at all) but he is strong defensively, can play all three outfield positions, and has developed this year into a good average hitter (he currently is cruising to a Southern League batting title). The D-backs probably wouldn't be concerned about him riding the pine, as he's a bit older (turns 28 soon) and isn't really expected to develop into much. But he would be useful if Prado had to move to the infield, and could be useful as a pinch hitter as well. Since he's right handed, it would help the unbalanced bench, and he's probably a better hitter than any of the above three at this point.
Chris Owings: A lot of fans would like this move, but the only way I see it happening is if the D-backs decide that Prado is going to be a full-time outfielder AND that Didi isn't going to get much playing time. Cliff Pennington then becomes the utility infielder (backing up Hill, Owings, and Davidson) and Owings slots in at SS. If this happens, know that the front office has officially given up on the season.